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Steven1994 Level 1 (0 points)



I have a Mac Pro Mid 2010 quad-core 3.2 GHz with ATI HD 5870 with 2 mini display ports and 1 DVI port.

I would like to connect at least 3 monitors : 2 Apple Cinema 30" (2 DVI dual-link ) and 1 Apple Cinema 27" ( 1 mini display port )


Can I install an additional new ATI HD 5870 within my Mac Pro?


Thank you for your help,

Mac Pro, OS X Mountain Lion (10.8.2)
  • The hatter Level 9 (60,930 points)

    Not w/o add'l power feeds, besides which yours can support 3 displays done right.


    And $449-ish for 2nd 5870? With ML maybe a low end GTX that does not need more power.


    Easier to just get the proper dual-link adapter.

  • Grant Bennet-Alder Level 9 (56,679 points)

    Here is "the company line" on supporting those displays:


    Mac Pro (Early 2009), Mac Pro (Mid 2010), Mac Pro (Mid 2012): Supported display configurations


    You can use third-party adapters, provided they are ACTIVE, POWERED adapters.

  • nextech Level 1 (35 points)

    > Can I install an additional new ATI HD 5870 within my Mac Pro?


    Yes, just make sure you buy one with EFI code in its bios.


    You might be able to get a cheap PC one and flash the BIOS (there's lots of guides on the internet, it's fairly easy).  Once the second 5870 has EFI code in it's BIOS then it boots happily into Mac OS X.


    See here:


    See here: 4CA9CXUKYX2JTT2XYP2UD97J2K9YC

  • Grant Bennet-Alder Level 9 (56,679 points)

    The second 5870 will require two 6-pin aux power cords that have nowhere to plug in.

  • nextech Level 1 (35 points)



    I have multiple video cards in all of my Apple Mac Pro's.


    The Mac Pro mainboard has two six-pin power ports (75W ea).  You use a Mac Pro PCIe 6-pin power cable such as this one here: -GeForce-8800-GTX-285-/160708022317


    If you already have a 5870 installed in your Mac Pro, then you probably already have two of the cables listed above already installed.  (with one cable going to each of the two 6-pin power connectors on the 5870 graphics card that you currently have installed).


    So for the first video card, you are drawing 150W (75W x 2) directly off of the mainboard, and then the card is drawing an additional 75W off the PCIe bus (the card slot), for a total of 225W (maximum).


    For the second video card, you are saying that you don't have any additional "6-pin" power cables to connect to.  Yes, this is correct.  What you do is simply get a 4-pin MOLEX to PCIe 6-pin (or 8-pin, which is 6+2 pin) power cable adapter.


    This will simply draw the power off of your 12V power supply leg and convert it so you can use it to power a second video card.


    You use this cable here for your second video card: 8A6Q


    It's about $6 for the cable, and it converts two (dual) 4-pin Molex (75W x 2) into dual 8 (6 + 2) pin PCIe power.  It has two connectors that can be used as either two 6-pin or two 8-pin connectors (6+2).  Some graphics cards (such as the Radeon HD 7970 require an 8-pin power connector, and a 6-pin, while other graphics cards such as the HD 5xxx series only require two 6-pin power connectors). 


    The adapter that I listed (for $6 at Fry's) will do exactly what you need it to do.  It will draw 150W of power (two 4-pin Molex) and convert it into two six-pin (or or one 6-pin and one 8-pin, or two 8-pin) connectors and you just plug those two six-pin connectors into your video card, and it will just draw the power from your 12V power supply leg (instead of drawing power off of your motherboard).  It's better to go directly through the power supply anyways. 


    The HD 5870 that you are talking about will specifically use two 6-pin connectors, so you just use the $6 cable adapter that I listed (from Fry's) and just use the two 6-pin connectors and plug them directly into your new second HD 5870 graphics card.


    If you were trying to get into the larger (and more "power hungry") video cards like the GTX 680 or GTX 690, or Radeon HD 7970 or HD 7990.  Those require one six-pin, and one eight-pin, so you would simply just use the same exact Fry's adapter, and draw the 8-pin power from the two 4-pin Molex (75W x 2 = 150W), then use a six-pin from your motherboard for the other 75W (and draw 75W off your motherboard).  If you want to install two Radeon HD 7970 graphics cards, then just buy two of these Dual 4-pin Molex to 8-pin (6+2) PCIe cables, and use one 8-pin for each graphics card, and then use one six-pin from each of two 6-pin ports on the motherboard.  That way you are "splitting" up the power and drawing the full 75W x 2 from the motherboard, and also separately drawing 300W (150W x 2) directly from the power supply.


    Your fans will generally use the 150W 8-pin connector (and that will draw directly off of your power supply) and the GPU itself will normally use the "clean power" coming off the 6-pin connector (and you can draw that directly from the motherboard).


    Hope this helps, and I hope this answers your questions, and that you can mark this question as "answered".


    Yes, I do have Radeon HD 7970's in all of my Mac Pro's, and yes I have replaced my older Radeon HD 2600XT's (in my 2008 era Mac Pro's) and the HD 5870's that I had in my newer Mac Pro's, with the newest Radeon HD 7970's.


    The Radeon HD 7970 GHz Edition is a much faster (and much more powerful) graphics card, and it whips the **** out of the old Radeon HD 5870's.


    The Radeon HD 7970 GHz Edition, does require an 8-pin and a 6-pin (instead of two 6-pins like the 5870).  Again, as I stated previously in my instructions, use the same exact Fry's cable that I showed you for $6, and that cable is capable of doing either two 6-pin, or two 8-pin.  It's a universal cable.


    Just make sure that when you are installing TWO graphics cards, always try to split up the power (evenly) between them.  Pull half of your power off of one power leg, and half of your power off of another power leg.


    So plug one six-pin from the motherboard into the GPU power connector (on each card), and then plug one six-pin connector into the 4-pin molex cable adapter (on each card).  That is what I do on all of my systems, and it has worked out extremely well, and it divides the power up evenly between the two power legs (the 12V direct power supply, and the 12V that is being drawn directly through the motherboard).


    Hope this helps, and if this answers your questions, please mark this as "answered" (solved your question).  Thank-you.

  • The hatter Level 9 (60,930 points)

    EVGA and others (MacVidCards) do not endorse or recommend such setups.


    What you do is simply get a 4-pin MOLEX to PCIe 6-pin (or 8-pin, which is 6+2 pin) adapter.


    You can't get more milk out of that cow than she has, and the molex feeds do not provide 150W.


    YOU MUST USE a 2nd PSU such as the 450W units that go into optical drive bay designed for GPUs and have pairs of 8-pin and 6-pin feeds.

  • nextech Level 1 (35 points)

    > You can't get more milk out of that cow than she has, and the molex feeds

    > do not provide 150W.


    Absolutely 100% not true.


    Each 4-pin molex supplies 75W (max) power.  Two 4-pin molex = 75W x 2.  (Do the math).


    Yes, I have 27 Apple Mac Pro's, and every single one of them are set-up this way, and I also have four Mac Pro's at home that are set-up this way, and yes it works, and it's completely safe, and I've never had a single problem ever.


    The Mac Pro power supply can easily handle two video cards.  If you split the power up (exactly as I told you in my message) then you are doing everything 100% safe.


    You are only drawing a MAXIMUM of 75W from your 12V direct power supply leg (one 6-pin connector), and you're drawing another 75W (maximum) power from a second 12V leg (directly off your 6-pin connector on your motherboard) and then you are drawing another 75W (maximum) power directly off the PCIe card bus itself.  So yes, you can safely draw 225W (maximum) and it's dividing it up between three seperate power legs, and it's perfectly fine, and perfectly safe.


    > YOU MUST USE a 2nd PSU such as the 450W units that go into optical drive bay

    > designed for GPUs and have pairs of 8-pin and 6-pin feeds.


    No you don't.


    Unless you're going to do EXTREME GAMING, and truly believe that you are going to be pulling 350+ Watts (through each of your two graphics cards), then yes you would/could possibly need a second power supply, but the Apple Mac Pro comes with a 1,000 watt power supply, and you can easily have 500+ Watts to play with (give or take), and installing two 5870's (which draw under 225W each MAXIMUM) are not putting you anywhere close to maxxing out your power supply.


    Now if you were going to try and do two HD 7990's or GTX 690's (in Dual-crossFire or Dual-SLI) and plan on MAXXING out your graphics cards (extremely heavy gaming) then yes, there is a possibility that you could smoke a power supply, or even damage a video card.  But you are not buying HD 7990's or GTX 690's (which are dual-GPU cards).  You are buying a small HD 5870 which is a SINGLE GPU graphics card, and the power requirements are much much lower.  (225W maximum).


    You'll never max out your power supply with two HD 5870's.  It's completely safe.  Just make sure you draw one six-pin connector (for each graphics card) off of your 12V (4-pin molex) leg, and then draw your second six-pin connector (for each graphics card) directly off your motherboard.


    That will split the power between the two legs EVENLY.  So the graphics card will draw the first 150W of power (75W x 2) from the PCIe bus directly.  If it needs more power (i.e. fans) then it can draw the second 150W (75W x 2) from your 12V molex leg, and the two GPU's will use the third power leg (using the two 6-pin connectors directly to your motherboard) and that will provide your third set of 150W power (75W x 2).


    Will the fans ever use 150W of power?  Absolutely not.  You're talking one or two 8watt fans (16 watts max).  So why on earth "The Hatter" is trying to SCARE you with saying you'll be drawing too much power is beyond me.


    Most graphics cards sit nearly idle (and draw less than 25W of total power).  Unless you are doing EXTREMELY HEAVY GAMING, and trying to burn up your graphics cards (for over an hour or two non-stop) then I honestly wouldn't be worried at all.


    If you plan on doing EXTREMELY heavy gaming, then I would be more worried about the COOLING (of the cards and the Apple Mac Pro case) then I would be worried about the power draw.


    The Apple Mac Pro power supply is more than sufficient for what you are trying to do.

  • nextech Level 1 (35 points)



    I have 27 Apple Mac Pro's (all running Radeon HD 7970 GHz Edition graphics cards) at the office, and I have four Apple Mac Pro's (all running Radeon HD 7970 GHz Edition) graphics cards at the house.


    As an example, I do have an old 2008 Apple Mac Pro with TWO Radeon HD 7970 GHz Edition graphics cards and one Radeon HD 2600XT (three graphics cards) all installed inside of one 2008 Apple Mac Pro.  (An old home computer at the house with THREE graphics cards).  I originally had three Radeon HD 2600XT's in the Apple Mac Pro (from 2008 when I bought it).  I later pulled two of the Radeon HD 2600XT's out, and installed two Radeon HD 7970 GHz Edition (and left one old Radeon 2600XT inside, for a total of three graphics cards).


    I do NOT use it for gaming, and I simply use it for daytrading/forex, surfing the web, watching Blu-Ray movies, burning movies, video/photo/picture editing, 3D modeling, CAD/CAM, etc.  I simply needed to power 12 or 14 displays, so I installed two Radeon HD 7970 GHz Edition graphics cards, and also left one of the Radeon HD 2600XT cards that originally came with the 2008 Apple Mac Pro.


    On the Radeon HD 7970's, I simply used two 6-pin power cables (that I mentioned in the first link above) to power each of the 6-pin (75W) connectors on each of the two Radeon HD 7970 GHz Edition graphics cards.


    I then used two separate Fry's cables (yes, I bought TWO of the Fry's cables) and used one cable (connected to two 4-pin Molex) which draws 75W (per 4-pin molex) x 2 = 150W, and it supplies a 150W (maximum) via the 8-pin power connector (plugged into one Radeon HD 7970 GHz Edition).  Then I used the another one of the Fry's cables, and did the same exact thing for the second Radeon HD 7970 GHz Edition.


    My second Radeon HD 7970GHz edition sits nearly IDLE (about 95% of the time) and draws nearly no power at all.  It is simply used as a second adapter, so that I can easily power 12 monitors on my Apple Mac Pro.


    I have NEVER used more than 85% GPU utilization (on my first HD 7970 graphics card, let alone got anywhere close to 100% GPU utilization on BOTH graphics cards).  So the power draw is extremely minimal, and the HD 7970's are actually MORE power efficient than the HD 5870's (since they have advanced power management, and the video drivers can actually shut down the GPU on the second graphics adapter to save power).


    But either way, two 5870's off of a 1,000 watt Apple Mac Pro power supply should not be a problem at all. 

  • nextech Level 1 (35 points)

    I'm an engineer.  It's not too difficult to calculate power draw.


    Two Radeon HD 5870's (as what you are suggesting) draw less than 166 Watts of power (yes, that is TWO of them), while near/at idle.


    If you are just surfing the web, checking e-mail, doing stocks/trading, watching movies, etc.  Then yes, your GPU will be fairly close to idle.


    Your power draw (on BOTH graphics cards will probably be under 200Watts combined).


    See here:,2422-20.html


    One single Radeon HD 5870 draws 141 watts of electricity.  TWO Radeon HD 5870's draw about 166 watts of electricity total (so only about 25 watts of power for the second Radeon HD 5870).


    Yes, two graphics cards actually use FAR less electricity than you would actually think.  The graphics drivers are designed to "power down" the second GPU (on the second graphics card), so you're really only using ONE GPU (from the first graphics card), and this is designed to save power.  (That is what Radeon's do).


    Even if you were doing EXTREME HEAVY GAMING (with maxxed out frame rates) and were trying to completely MELT your Apple Mac Pro (and start a fire) the maximum power draw, would be 561 watts (using both graphics cards with BOTH GPU's at 100% utilization).


    First off, if you were actually trying to do that, I would be more worried about the HEAT being generated than actual power draw.  The heat being generated, would probably degrade the performance of your computer, and I would be far more worried about the cooling, then I would be about the power draw.


    But with your interior fans running (full blast), and your graphics cards fans (running full blast) the Apple Mac Pro might get a little bit noisy, but it should easily be able to handle two Radeon HD 5870's (fully maxxed out with both GPU's running at 100% utilization).


    I'm not saying that you should do it, but yes it could be done.  The Apple Mac Pro has a 1,000 watt power supply, and you won't be anywhere near close to maxxing out your power supply.  (Even at 80% or 85% energy efficient power supply, you're still left with 800-850 "usable" watts of power.  Which will leave you with about 600-675 watts of "peak power" for your graphics cards.


    If you are truly into HEAVY gaming, then just be careful (if you are always running at 100% GPU utilization on both GPU's) but I honestly don't know of anyone (other than heavy gamers) that are pushing their graphics cards anywhere near 30% utilization.  (Even while watching a Blu-Ray movie and doing H.264 decoding).


    Having two graphics cards will simply do nothing more than have the first GPU run (until it gets close to 85% utilization, and then it may split the utilization over to the second GPU) but the drivers are designed for ENERGY EFFICIENCY and it usually keeps the second graphics card powered down nearly all of the time (to save power).


    If the first GPU is near max utilization, then it will power up and use the second GPU (to handle the extra load) and even with BOTH GPU's running at 100% utilization, and all of the fans running at full blast, you're still under 561watts of MAXIMUM power draw (on two Radeon HD 5870 graphics cards).


    With a 1000 watt power supply in an Apple Mac Pro, you should be fine.  I'm not suggesting that you use the computer for heavy gaming, but if you are just looking to power a few extra monitors, it's fine.


    I have three graphics cards in my Apple Mac Pro, and I'm powering 12+ monitors, and I'm not having any problems with heat, or GPU utlization, or power.  Nothing.


    My GPU's are constantly idle, and two GPU's are completely idle, and the first GPU (on my first Radeon HD 7970 graphics card) is under 15% utilization at all times.  Even if I'm watching TWO Blu-Ray movies (at the same time), my GPU utilization never goes above 35% on my first graphics card, and my second (and third) graphics card continue to remain idle.


    So unless you're doing massive/severe 3D rendering (or heavy computer gaming), I don't foresee any problems with running multiple graphics cards. I have always had THREE graphics cards in eight of my Apple Mac Pro's, and I've never run into any issues with power, or heat.  The GPU's on two of my graphics cards sit completely idle, and the GPU on my first graphics card normally doesn't go above 30% utilization (even with heavy CAD/CAM drawing).


    If we're doing severe rendering, then we crank up the Air Conditioner (to about 50 degrees F) to keep the rooms extremely cool, and we can bump up the GPU utilization to about 85% on two GPU's and the Apple Mac Pro still stays fairly cool.  The third graphics card stays idle nearly 100% of the time, and we've never been able to go beyond 85%-90% GPU utilization (even on two GPU's, let alone three).


    So I honestly don't think that you (as a non-gamer) would have any problems.  Again, you're only trying to run two HD 5870's, and I'm running two HD 7970's GHz Edition, and also one Radeon HD 2600XT (three graphics cards).  So I think you should be completely fine, since you are using far less power draw then I am.  My Apple Mac Pro is maxxed out with dual Blu-Ray burners, 4 hard drives, and completely maxxed on RAM.  I'm not having any problems with power (but the only issue is heat/cooling when you're running at 100%).  Be sure to keep the room fairly cool/cold if you are going to be trying to use this machine for heavy gaming or extremely intensive 3D rendering.  That's my advice to you.


    But yes, if you're just power extra monitors, that is nothing, and that won't even use ANY GPU utilization on your 2nd GPU.  So adding a second or third graphics card, would only add about 25 watts of power load on top of your first graphics card power load.  So if you factor your first graphics card (at maximum 100% GPU utilization) will draw about 354 watts of power, just add in 25 watts of additional power for each of the additional graphics cards that you add (since they will just remain idle all the time).  So even two additional graphics cards, would only be about 404 watts of power draw (with 100% GPU utilization on your first graphics card).  Your 2nd and 3rd graphics cards will continue to remain idle (to conserve power).  So you're fine.  No reason to have three GPU's running, when you can do almost everything all on one GPU.  That's the nice advantage of Radeon.  ;-)


    The Radeon's are extremely energy efficient.


    <Edited By Host>

  • nextech Level 1 (35 points)



    It really all depends on what you're trying to do (and what you need the 2nd graphics card for).  If you are just looking to power a few extra monitors then just adding a power splitter (like the $6 Fry's adapter that I mentioned) is sufficient.


    If you are trying to do HEAVY GAMING, and believe that you'll be using the graphics cards (in CrossFire mode, under Windows for playing heavy gaming) and believe that you'll be utilizing/maxxing out both GPU's on both cards, then yes I would suggest a 2nd power supply.


    We do quite a bit of CAD/CAM work, and 3D animating/rendering, and I also have a few machines that I use for daytrading/Forex, but I never really get above 50% or 75% GPU utilization (on my first GPU) and I never really max the first GPU, let alone use the GPU's on the second or third graphics cards (under normal usage).


    If you believe that you are going to be doing heavy gaming, or heavy 3D rendering, then get a "JuiceBox" power supply (450Watt), and they run about $24.  Just stick it into an unused 5 1/4 bay slot (if you have a spare slot open).


    Related links:

    2 HD 5870s in 2010 MacPro


    Wiring external PSU to MP 2009?


    can i use an external power supply to power second graphics card?


    Precise instructions for getting x2 ATI Radeon HD 5870's in your Mac Pro (2009-2010)


    I hope that this answers all of your questions, and that you can mark this thread as "answered/solved".

  • nextech Level 1 (35 points)



    Most of the talk about needing a second (or third?) power supply to power a graphics card is complete nonsense.  It really depends on what you are using/needing the graphics card for.


    I have 27 Apple Mac Pro's at the office, and have four Apple Mac Pro's at home, and I've always had THREE graphics cards in several/most of my computers, and dating all the way back to 2008 I was able to buy a 2008 Apple Mac Pro with three Radeon HD 2600XT graphics cards already in it (just added 2 additional graphics cards).


    A Radeon HD 2600XT uses about 18.1 watts (while doing 2D work) and while doing 3D rendering under 100% full GPU utilization uses 54.4 watts.


    See here:,2122-6.html


    Three Radeon HD 2600XT's normally use about 60 watts of power (while doing 2D work) and even with all three graphics cards (in CrossFire) at 100% GPU utlization, I was hovering around 162 watts of power draw (with all three GPU's maxxed out at 100% GPU utlization).


    Newer graphics cards are far more powerful but also have much better power management (and they can shut down the unused GPU cores) and they reduce the power consumpion (on idle GPU/graphics cards) to almost zero, and your 2nd and 3rd graphics cards usually never use above 25 watts of power.


    In 2012, decided to upgrade to an Radeon HD 7970 GHz Edition.  This is a much faster GPU, and just ONE GPU on one Radeon HD 7970 is far more powerful than all three GPU's using three Radeon HD 2600 XT's.


    I also replaced several older Radeon HD 5870's with the latest Radeon HD 7970's because I can do more with one graphics card, then I could with two or three Radeon HD 5870's (while actually using less power).


    So now, in most of my machines, I have two Radeon HD 7970's and one Radeon HD 2600XT.  The Radeon HD 2600XT's were just leftover graphics cards from the older 2008 and 2009 Apple Mac Pro's.  I put one Radeon HD 7970 (in slot 1 which is a double slot), and have one Radeon HD 7970 in slot 2 (which takes up slots 2 and 3).  I have a Radeon HD 2600XT in slot 4.  (This gives me the ability to power 12-14 monitors)


    In my opinion, the graphics cards are way too close together for proper cooling, and you really need an EATX motherboard (like an EVGA SR-X) with seven PCIe slots, so that you can space out your graphics cards (for proper cooling) or use water cooling (like on most gaming machines), if you are truly interested in building a "gaming machine" (for extreme 3D rendering/gaming).


    If you are just looking to power a few extra monitors (while just surfing the web, or doing standard 2D desktop work) then your second and third graphics cards will be sitting completely idle (~18 watts to 25 watts of power consumption for each of your 2nd and 3rd graphics cards in CrossFire mode).  The graphics cards will remain cool (and silent) and you won't have any problems.  Your first primary graphics card could consume anywhere between 18-25 watts (idle) and 54 watts (maximum) on a Radeon HD 2600XT.  On a Radeon HD 5870, you're talking 166 watts (83 watts per graphics card, while idle), and about 340-360 watts (83 watts + 280 watts) with one GPU at 100% utilization.  If both GPU's are both running at 100% full utilization (under CrossFire) and fans are blowing at 100% full speed, then you could draw as much as 561 watts (for two Radeon HD 5870's in CrossFire mode). 


    Your power draw (on BOTH graphics cards will probably be under 200Watts combined).


    See here:,2422-20.html


    If you truly believe that you'll be running your GPU's (in CrossFire mode) at 100% GPU utilization (and trying to start a fire) then sure, get a 2nd power supply.


    But even if you bought a second power supply, what is that going to do?  Not much of anything, other than start a fire.  Truly, if you are maxxing out your 1000Watt Apple Mac Pro power supply, and you feel that you need another (2nd) 450 watt power supply, and truly think that you are using 1450 watts of power, then you are probably going to start an electrical fire in your room (unless you have a dedicated 15 Amp circuit just for your computer and the two power supplies). 


    Keep in mind that a typical 15 Amp circuit (using 14 gauge wire) can have a maximum draw of 12 amps or 1440 watts.  (Never go above 80% of the max watts, so 15 x 120 = 1800 watts x 0.8 = 1440 watts)


    If you are going to draw more than 1440 watts (this is including your ceiling lights, computer monitors, speakers, printer, and EVERYTHING in your room and EVERYTHING on that circuit), then you need to re-wire your house/room and put in a dedicated 20Amp circuit (just for your computer) if you truly think you are drawing that much power.


    Yes, in server rooms we use dedicated 20Amp circuits for each server (because of the multiple CPU's, and multiple hard drives used in RAID arrays, and often two redundant power supplies).  A 20 Amp circuit will give you about 20 x 120 = 2400 watts x 0.8 =  1920 watts (continuous)


    Anytime you add a second power supply, you are using/losing more electricity.  Most home power supplies are about 80% to 85% efficient.  Some server power supplies can be as high as 90% or 95% efficient.


    As a safe guess, just figure 1000 Watts on a Mac Pro x 80% efficient, and figure you have about 800 watts of "usuable" power.


    That should be sufficient for three graphics cards (doing normal 2D work), and even if you were doing 3D work it's highly unlikely that you would EVER max out the GPU on one single Radeon HD 7970 graphics card.  If you were doing something requiring that much rendering power, and ended up using/requiring a second GPU to actually be used, then yes your power requirements would go up a bit.


    But normally your GPU's on your second and third graphics cards will be completely idle, and you'll never go above 25 watts (for your 2nd and 3rd graphics cards).


    If you truly think you'll be trying to "render the whole world" on your Apple Mac Pro (and doing some SERIOUS 3D GAMING, and you have a nice 16K16K wall of monitors) and you somehow are trying to squeeze every single last frame per second you can out of your computer, then yes... you have a good chance of melting your Apple Mac Pro, and starting an electrical fire in your home).


    You may want to consult with an electrician and tell him that you need a dedicated 20Amp circuit just to plug your computer in (for your 1000 watt primary power supply, and 450 watt secondary power supply and UPS and enough power to power all of your monitors/displays).


    But in 99% of the cases, if you are just primarily using your monitors/displays for just surfing the web, or doing Microsoft Word, Powerpoint, Excel, or just normal desktop applications (2D) then you are using very minimal power on your graphics cards (especially since your 2nd and 3rd graphics card will always be idle).


    I have three graphics cards in nearly all of my 27 Apple Mac Pro's, and I've never run into any problems.  I don't have a second power supply in 25 of them, and there are only two Apple Mac Pro's that we have a 2nd power supply in (and those two are used specifically for rendering).  Those two have dedicated 20 Amp circuits, and we have them in a room with extra cooling (dedicated A/C unit to keep the room temperature at 50 degrees or lower).


    I'm fairly confident that just getting a $6 power adapter from Fry's will be sufficient for what you are trying to do (unless you are a heavy gamer).  If you are a heavy gamer, then look into getting a "Juice Box" (450 watt) power supply to power your second graphics card, and also look into getting your house/bedroom wired for a second dedicated 15 Amp circuit just to power your computer (and your two power supplies) because if not, just like The Hatter said:


    "You can't get more milk out of that cow than she has,"


    You can't squeeze more power/amps out of a circuit than you have.  You'll either overload the circuit, pop a circuit breaker, or start an electrical fire.


    But two Radeon HD 5870's are nothing.  Even two Radeon 7970's are nothing.  If you were looking at three GTX 690's or three Radeon HD 7990's (which are dual GPU cards) then yes I would be a bit concerned about power, and yes you'll probably need quite a bit of juice (a dedicated 20 Amp circuit breaker, and an additional 450 watt or possibly even an additional 1000 watt power supply) depending on what you are doing with the graphics cards.

  • Steven1994 Level 1 (0 points)

    Thank you all very much for your help.


    I would like to refine more my requirements.


    In fact, I'm not a gamer at all, it is not for Heavy Gaming.


    I just need power configuration for using a lot of charting for daytrading in Forex, Stock, Futures.


    my system configuration are :

    - 1 Mac Pro mid 2010 Quadcore 3.2GHz, 16 GB RAM + ATI Radeon 5870 ( 2 mini DP + 1 DVI )

    - 1 PC i7 windows 7


    with 5 screens :

    - 2 Apple Cinema 30" (2 DVI)

    - 1 Apple Cinema 27" (mini display port)

    - 1 iMac 27" (mini display port)

    - 1 Samsung 27" ( DVI,HDMI,VGA) for PC .


    I need confirmations for  2 points :


    Point 1 : I think I can to connect to Mac Pro the following 3 screens : ( for the time being)

                -  1 ACD 30" (DVI)          --> DVI port

                -  1 ACD 27" (miniDP)     --> mini display port

                -  1 ACD 30" (DVI)          --> mini display port  via  Apple Mini DisplayPort to Dual-Link DVI Adapter


    The question is :

    - as Apple Mini DisplayPort to Dual-Link DVI Adapter already cost 99$, is it not worth to buy another ATI 5870 in order to able to connect more screens in future?


    Thank you for your help,

  • nextech Level 1 (35 points)



    Even if you had two Radeon HD 7970's and one Radeon HD 2600XT graphics card (three graphics cards) in your computer, you'd still be using under 361 watts under normal utilization, and that is running 3DMark 11 Deep Sea and Temple Demo (on graphics card #1 at full 100% GPU utilization).


    While graphics cards #2 and #3 sit fairly idle (at 99 watts, and 18 watts respectively).  So you're still using 241 watts + 99 watts+ 18 watts = 359-361 watts of electricity (with GPU #1 at full 100% utilization, and GPU #2 and GPU #3 idle).


    If you were trying to do some SEVERE gaming (or severe rendering) where you believed that you could max out all three GPU's, then yes I would definitely suggest a second 450 watt power supply just to handle the second Radeon HD 7970 graphics card (you could probably peak out at 314 watts on a Radeon HD 7970 running at 100% GPU utilization and with fans blowing full blast).  Two of them running at 100% GPU utilization could probably hit about 618 watts.  If you throw in a Radeon HD 2600XT on top of that, you're already looking at about 672 watts (or close to 700 watts).  So yes, a second power supply would definitely be necessary.


    So it all really depends on what it is that you're trying to do.  Heavy gaming, and heavy 3D rendering, then yes get a second power supply.  Follow the instructions I posted above.


  • nextech Level 1 (35 points)



    You are in the exact same boat that I am in.  Yes, I use MetaTrader 4, and I have a 12 monitor configuration (using Ergotron quad-racks) and have four monitors (mounted in a portrait-style position) in one rack, and I have three of the quad-racks on my desk (a standard heavy duty 72" folding banquet table, pressed up against a "wrap around" desk).  So I do have two 30" monitors on my desk, and then have twelve 22" monitors (in three quad-racks).  So yes, you can easily power 12-14 monitors running off of an Apple Mac Pro (if you're just doing trading/Forex, etc.)


    Standard 2D work, you are fine.  My GPU on the my first graphics card really never gets above 75% (ever).  The second and third graphics cards just sit idle and do nothing.


    Get the second HD 5870, and just use the $6 power splitter cable from Fry's and you'll be fine.

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