Running 2 Nvidia GTX470's in a Mac Pro ?

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Running 2 Nvidia GTX470's in a Mac Pro ?

Hello,

I recently acquired TWO Nvidia GTX470's as a gift. I would like to run in a new Mac Pro 8-core 2.4Ghz Westmere (2010). I would like to do this in order to switch easily between AE, Nuke, etc. and Davinci Resolve, so one would be attached to the monitors and power Adobe's 64bit Mercury engine and the other would just be there to give CUDA support for the Davinci. Obviously there are a few issues.

1) Since the GTX 470's need 2 power cables (6 pin) can I run off of the Molex connectors in the optical bay (not sure how many are there) and evenly distribute the load by using 1 connector from the motherboard and the other from the Molex for each card?

2) I have heard the 2010 Mac Pro's have the capacity for 2 PCIe x16 slots and that unlike previous generations these can be any 2 slots you chose. This would be ideal as I would like to put these doublewidth video cards as far apart as possible in order to keep heat down and let the fans do their thing. Can anyone confirm this?

3) If I am forced to provide an additional power supply (even though the Mac Pro PSU is 1000w and should technically be able to handle this additional video card) what would be recommended? I have heard the visiontek/epower 450w unit (which fits into an optical bay) is quite awful and uses substandard parts as well as kicking a lot of heat back into the machine, so is there another alternative which does not require leaving the side door open or drilling holes in my new Mac Pro?

Thanks for your patience if this topic is redundant. Need to be as thorough as I can here.

Color, Mac OS X (10.6.7)

Posted on Sep 21, 2011 12:12 AM

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Answer 1

X423424X

Level 6

14,271 points

Sep 21, 2011 12:44 AM in response to yoclay

1) Since the GTX 470's need 2 power cables (6 pin) can I run off of the Molex connectors in the optical bay (not sure how many are there) and evenly distribute the load by using 1 connector from the motherboard and the other from the Molex for each card?

The Mac Pro comes with two power adapters. So that limits you to one card. The only way you could power the other card is with an additional PSU. I've seen posts where this has been done. Attempting to split the power adapters to drive both cards will exceed the power capacity of the mac pro's power supply.

2) I have heard the 2010 Mac Pro's have the capacity for 2 PCIe x16 slots and that unlike previous generations these can be any 2 slots you chose. This would be ideal as I would like to put these doublewidth video cards as far apart as possible in order to keep heat down and let the fans do their thing. Can anyone confirm this?

I believe slots 1 and 2 are x16 and slots 3 and 4 are x4.

Relating to the issues of both power and slots you might want to read this apple discussions thread.

3) If I am forced to provide an additional power supply (even though the Mac Pro PSU is 1000w and should technically be able to handle this additional video card) what would be recommended? I have heard the visiontek/epower 450w unit (which fits into an optical bay) is quite awful and uses substandard parts as well as kicking a lot of heat back into the machine, so is there another alternative which does not require leaving the side door open or drilling holes in my new Mac Pro?

That apple discussions thread I referenced above has some info on what someone was planing on using.

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Answer 2

yoclay Author

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Sep 21, 2011 2:55 AM in response to X423424X

Interesting, because the thread you linked to seems to indicate that x16 slots are completely interchangeable with a limit of 2 wherever you would like. What is the official Apple word on this?

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Answer 3

X423424X

Level 6

14,271 points

Sep 21, 2011 3:30 AM in response to yoclay

I think this info is coming from an (older?) apple doc referenced in that other thread:

Mac Pro: About the PCI Express slots

Specifically the section near the bottom about 2009 Mac Pros:

This applies to later mac pros as well.

From the Apple Mac Pro technical specs, PCI Express expansion section:

They only say one x16 there because they mention the other x16 in the graphics section. Maybe some of the confusion comes from that last line about "mechanical support".

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Answer 4

yoclay Author

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Sep 21, 2011 5:34 AM in response to yoclay

Still looking for an alternative (available in Europe) to the Visiontek 450w (now Epower). Anything else out there that doesn't require wires coming out of the back of my machine or leaving the side door open?

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Answer 5

The hatter

Level 9

61,031 points

Sep 21, 2011 8:17 AM in response to yoclay

Anything you do, will be messy looking and tangle of wires I am afraid.

There are some photos of what users have done on

Mac Pro Rumors

Would be nice to gut and replace the Apple PSU for 1200W with plugs needed.

Or a case.

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