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Old Jan 10, 2013, 10:40 AM   #1
InuNacho
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Has anyone tried this Dual 5870 setup?

Last month I picked up a Quad 3.33 4,1 at a price that couldn't be beat and then just last week found a rather cheap official 5870. The 5870 fits my Mac needs perfectly, but I'd like to play something more graphics intensive on the Windows side.

I've seen the threads about adding a second PSU but I found this article on Hardmac that says you only need to use a Sata to molex cable and some other stuff to get it to work. I don't know much about the innards of my Pro and I'd like to use all four HD bays and have a SSD in the second optical bay, would I be able to use the second ODD port to power the card?

Finally would adding a card like a Blackmagic Intensity Pro cause any ventilation issues and could a cheapo PCI fan fix any issues that would come up?
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Old Jan 10, 2013, 12:39 PM   #2
DanielCoffey
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The second 5870 will need another 2x 6-pin power leads which you just don't have unless you go for the secondary power supply. You can't run all that from a molex connector.. well, not for very long...
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Old Jan 10, 2013, 12:53 PM   #3
All Taken
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Originally Posted by DanielCoffey View Post
The second 5870 will need another 2x 6-pin power leads which you just don't have unless you go for the secondary power supply. You can't run all that from a molex connector.. well, not for very long...
I've run a GTX 680 and a 5770 using SATA to 6 pin from the 2nd hard drive slot. No problems here but nobody really knows what the limits are as nobody has ever tested the maximum trace load.

In short OP, I ran a GTX 680 and 5770 comfortably and could have drawn power from the ODD bay along side several SSD drives but that would be messy in the cable management.

I wouldn't recommend the draw of 2 5870's, I'm sure the PSU can handle it but factor in that the Processor/s draw, memory, hard drives, ssd's, USB devices etc etc and you might be in trouble, fizz bang trouble. If you want to draw extra power the safest option is via the SATA to 6 pin route, purely because if you over draw it is far more likely to flick a relay than if you split the 2 x 6 pin and burn out the traces/your video card.

If you decide to do this I'll give you a copy of HW monitor pro for mac so you can screenshot your power distribution and load. If you don't do this, I understand and hope you find a solution for your needs.
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Old Jan 10, 2013, 01:07 PM   #4
JuniperMonkeys
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Like others said, powering two 5870s wouldn't be ideal. It's fairly easy to find auxiliary power supplies that fit in the free 5.25" bay, though. The cord comes in through one of the case's PCI slots, so you don't have to do anything nutty like leave the side panel off. However, they tend to be noisy due to small fans.

FWIW, I tried this setup, got frustrated with the drawbacks, and got a single EVGA 670. PC 5870s are so cheap now, though...

It will probably go without saying that the second 5870 does nothing in Mac OS, since Crossfire isn't supported.
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Old Jan 12, 2013, 10:27 PM   #5
InuNacho
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Originally Posted by JuniperMonkeys View Post
Like others said, powering two 5870s wouldn't be ideal. It's fairly easy to find auxiliary power supplies that fit in the free 5.25" bay, though. The cord comes in through one of the case's PCI slots, so you don't have to do anything nutty like leave the side panel off. However, they tend to be noisy due to small fans.

FWIW, I tried this setup, got frustrated with the drawbacks, and got a single EVGA 670. PC 5870s are so cheap now, though...
Noise along with possible sleep issues are why I wanted to avoid a second power supply. It's quite unfortunate considering that a PC 5870 can be had for less than $80 if you look around.

Quote:
Originally Posted by All Taken View Post

I wouldn't recommend the draw of 2 5870's, I'm sure the PSU can handle it but factor in that the Processor/s draw, memory, hard drives, ssd's, USB devices etc etc and you might be in trouble, fizz bang trouble. If you want to draw extra power the safest option is via the SATA to 6 pin route, purely because if you over draw it is far more likely to flick a relay than if you split the 2 x 6 pin and burn out the traces/your video card.

If you decide to do this I'll give you a copy of HW monitor pro for mac so you can screenshot your power distribution and load. If you don't do this, I understand and hope you find a solution for your needs.
It's tempting to give it a try but I think your right and it shouldn't be bothered with. It's nice that you got a 680 and 5770 working at the same time.

Thank you all for your input.
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