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Using PCI-E adapters with high end graphics cards

Last response: in Graphics & Displays
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July 12, 2012 10:22:48 PM

Hey guys.

I have a couple of questions and wonder if any of you kind fellows could throw me some of your knowledge about powering SLI with PCI-E adapters.

I recently acquired a second Asus GTX580 DCII for SLI in my rig. Now, my power supply (Coolermaster Realpower M1000) is somewhat of an older model so the PCI-E connectors on it are only PC-E 6pin x2 and PCI-E 8pin x2. The GTX580 DCII in SLI uses 4x 8pin PCI-E connectors.
So what i did was use two PCI-6 pin to PCI-8 pin adapters made from a company called Startech I believe. (http://www.amazon.co.uk/Startech-Express-Power-Adapter-...)

They appear to be decent quality with good gauge cables and i plugged them one in each card to spread the power.
I was considering getting a 1200w or something to power the cards but after digging on the internet and looking at the PSU specs of my Coolermaster, it appears to have plenty of juice with 80a on the combined 12v rail. I have tried these two 580's for two days pushing them on battlefield 3 @ ultra with this power supply and it seems perfectly fine. But the PSU keeps popping up in my mind...
What I would like to know is, is this safe? I doubt its recommended, but it works... could there be dire effects? is my PSU adequate?

Maybe i'm wrong, I don't know much about adapters and its been a looong time since I did any SLI.
If this is dodgy or maybe even dangerous I will fork out for another PSU, but if it's not necessary then I won't bother, being poor and all that. (by splashing out on video cards....ah the irony).

Also another question, probably a stupid one... If i was to run Nvidia Surround in future (three monitors) for gaming, does that use any more power from the systems PSU? I know the monitors obviously plug into the wall but i was wondering if there would be any extra power drain?

Thanks in advance for any help guys.
a c 117 U Graphics card
July 12, 2012 10:39:46 PM

The PCIe 6 pin adapters are designed to safely provide 75 watts of power, the PCIe 8 pin adapters are designed to safely provide 150 watts of power. The actual pinout difference is negligible (3 +12v and 3 ground vs 3 +12v and 5 ground) so a good power supply with good cables should be able to provide 150watts of power across a 6 pin without issue.

If you're concerned that it might be causing problems you should check the 12v rail measurements using HWInfo64 and ensure that they're not fluctuating too heavily. Also consider feeling one of the ground cables to ensure that they're not getting too hot. Also take a look at any reviews of that PSU and see what they say about the voltage stability as it approaches 100% load on the 12v rail.
July 12, 2012 10:56:52 PM

Thanks for the quick response.
I just checked the 12v on HWInfo64 while the cards are on load and the 12v doesn't appear to be fluctuating at all. Also the ground wires are warm but certainly not too hot to touch so i think i will be fine :) .
Thanks for the help man. I probably worry too much. Much Appreciated
a c 117 U Graphics card
July 12, 2012 10:59:39 PM

Supahgl00 said:
Thanks for the quick response.
I just checked the 12v on HWInfo64 while the cards are on load and the 12v doesn't appear to be fluctuating at all. Also the ground wires are warm but certainly not too hot to touch so i think i will be fine :) .
Thanks for the help man. I probably worry too much. Much Appreciated


Yeah if it's a decent quality PSU and the wires aren't too hot you should be good to go. 8->6 pin adapters are fine to use (many top quality PSUs have only 8 pin connectors with 2 pins separable) but 6->8 pin adapters can only be used with a high quality PSU.

If you're concerned you can always call Coolermaster's customer service and ask a tech.
!