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2 HD 5870s in 2010 MacPro

I'm looking for some info on a two 5870 crossfire set up. There is already one 5870 in my system. I'm thinking I'm going to by a auxiliary PSU to go into the empty drive bay( http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=56810 47&SRCCODE=GOOGLEBASE&cmmmco=VRqCjC7BBTkwCjCECjCE)

Does any one know how difficult this installation will be or if there is a superior option?

Thanks

2010 MacPro, Windows 7

Posted on Sep 20, 2010 9:52 PM

Reply
38 replies

Dec 1, 2010 11:39 AM in response to StooMonster

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.

Dec 27, 2010 11:44 PM in response to schulmaster

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 :]

Dec 28, 2010 12:23 AM in response to Lyon4a2

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.

Jan 15, 2011 1:43 PM in response to schulmaster

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.

2 HD 5870s in 2010 MacPro

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