2 HD 5870s in 2010 MacPro

Put a KillAWatt on your external PSU and see just how much you will need to "borrow" and whether it is safe to expect one cable to deliver twice as much power.

Don't worry about your VelociRaptors, those are light weight on power and SSDs must be as close to zero as you can go. Maybe 64GB RAM would make a dent though.

Awesome. Glad it is working for you.

Of course, try this on a custom GAMING PC and see the difference.. like the 09, the 2010 makes it very difficult to make a pathway for the wires from the 2ndary power supply to plug into the 5870.. but on a PC, there is no hinderance.

I am curious to hear more about your set up and the pros/cons. Especially with the Y-splitter and what you've used to add sata power in your box. (Splitters, I'm guessing?)

I am currently running a late 09 with a 2.93, 6GB, Crucial SSD boot, and a 5870. The 5870 is pushing 3x Dell Ultra-Sharp 23's and has some unusual behaviors. Triple display in either OS X or Win7 runs seamlessly, including very high performance Eyefinity array in Win7.

However.

I have to physically disconnect the two tertiary displays when rebooting, or the system will not recognize my videocard. I currently have one display connected by DVI, and the other two via Mini-DisplayPort to DisplayPort.

This is not necessarily ideal, and I was wondering if anyone has found a work around to that.

In regards to the Mac Pro not being a gaming machine, I think most of us refuse to accept compromises in a $4,000 workstation and/or don't feel like dropping an extra couple grand to buy a Windows machine to act as as a space heater while we're doing the majority of out computing work. Stow the judgement, and support the people who are pushing the limits of what the big silver beast can do.

As I wrote above, I use an external dedicated GPU power supply -- I had one in a cupboard from the days when PCs didn't have PSUs big enough for SLI/Crossfire; I run the two power cables in through the top PCI slot as I've not got a card in there.

It's one of these
http://www.thermaltakeusa.com/product/Power/PurePower/w0099/w0099.asp

So TECHNINCALLY, it IS possible to crossfire em? All you need is 2 y splitter cables to produce power to both cards?

Message was edited by: elpepemonster

Your 6-pin doesn't output enough, yes one low end card is possible, just not dual 5870s.

Those y-splits for 6-pin aux I can see with 8800GT which needs only one.

You can't get twice what they are designed for.

What you need is 2nd PSU, such as 450W that goes in optical bay - and deal with how to get the power cables down to the card.

I have the same issue as the person who posted this. I want to run 2x5870s, but is it ok to run two Y-splitter 6-pin 75W to power two 5870s?

Also this is in the specs page of the 2010 Mac Pro:
"All slots provide mechanical support for 16-lane cards. 300W combined maximum for all PCI Express slots"

Does that mean that you can run two cards at x16 bandwidth? Also I am a high-end gamer running BootCamp and playing AvP all maxed out ^_^

I appreciate any input :]

but is it ok to run two Y-splitter 6-pin 75W to power two 5870s?

No. The 5870 has two auxiliary power cables because it needs more than 75 watts of auxiliary power. It can also get 75 watts from the PCI-e bus, so one card needs more than 150 watts. There is a total of 390 watts available, which is not enough for two 5870s, no matter how many splitters you use.

Also this is in the specs page of the 2010 Mac Pro:
"All slots provide mechanical support for 16-lane cards. 300W combined maximum for all PCI Express slots"

Does that mean that you can run two cards at x16 bandwidth?

Yes, but not if the total power consumption is more than 300 watts. You can use two 5770s, but not two 5870s.

The only way is to add a power supply.

Hi again,

Just wanted to tell you a friend of mine who has 4 6890's crossfired in his PC can beat a mac pro hands down... Serious gaming demands a PC.. While Mac Pro can do the job, so much better performance on the PC for gaming..

Score one for the PC and WINDOWS 7.

Malcolm,

Can I just replace my stock PSU with whatever I can find? or has to be something specific due to Apple's specificity?

Thanks,
Lyon4a2

Here's a cookbook start to finish of the process, including pix. Fair warning: I haven't done this, 12 core Mac Pro with a single 5870 here.

http://forums.macrumors.com/showthread.php?t=1076970

Personally, a waste of time and money.... Get a gaming PC.. its better Gaming will NEVER EVER be popular on the mac platform.. Gaming will and always will be on a PC...Its not in Apple's ideology.

You can do it, but i'd suggest hotwiring an external PSU. I am currently running 2 5870 Eyefinity 6 Editions in my other mac pro. The downside of that is it does NOT run under Mac OS X with that setup... But oh well.

For you, I'd recommend getting the Antec 1200W PSU. Thats the one I'm using, and I use it because I can reuse it if I go to build a PC later on. It powers a whopping 4 high-end cards, with up to a total of 8 8-Pin PCIE Power connectors.
Now if you don't plan on going that far, any external PSU should be pretty sufficient for a second 5870. Hotwiring the PSU is as easy as taking a wire or a paperclip, and inserting it in to the right places on the ATX Connecter thing. I don't think much voltage goes through there at all. I've messed with it a few times on my external PSU and I didn't feel anything.

And btw, you do NOT need an Apple 5870 for the second 5870. ANY 5870 will work fine for crossfire. You can find 5870's on Ebay for between $200-300 now.

And btw, you do NOT need an Apple 5870 for the second 5870. ANY 5870 will work fine for crossfire. You can find 5870's on Ebay for between $200-300 now.

These are PC Flashed... Mac related ones demand a royalty.