780 SLI rebooting pc

L

[L]imey

[H]ard|Gawd
Joined
Jan 9, 2009
Messages
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Problem with my 780 Lightning SLI after adding kraken g10's to them.

When running SLI, the computer restarts after putting it under load. Does not happen with single GPU. Temps aren't reaching 50 before this happens.

Returned everything to stock clocks, same issue.

I upgraded my PSU to avoid issues like this, and no luck. 1000w evga supernova

Reinstalled drivers, no help.

Thoughts on what to try next?
 
This issue did not occur before you put the Krakens onto the cards?

Are you certain the card's VRMs are sufficiently cooled?

What mobo?
 
No this issue did not occur prior to this. I ran the cards individually with no problem.

The lightning has vrm heatsinks by default and they are not measuring higher than 45 degrees.

ASRock extreme 3 z77

When both cards had the stock coolers, there was no issue. Then again I was on a 750w corsair.

I struggle to believe that my psu is the issue, but I might swap the corsair back in just to test it
 
Just for shits, try pulling out all but one stick of ram and testing them one stick at a time and a load on your sli setup. Start narrowing down hardware.

Have you ever updated the bios on that mobo?
 
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Yeah the bios is up to date. Trying a clean install on a spare hd. After that will check the ram
 
Ugh... SLI/CF issues are so frustrating. I was thinking maybe one may have been damaged during the kraken install, but you said you tried them both individually and they can run loaded, so that doesn't make sense.

Both cards definitely have the same VBIOS version?
 
Ok, list of attempted fixes:

1 stick of RAM, no help
New Windows Install, no help
Different PSU, no help (the 750 ran both cards at stock before when I first got them)
Reseated everything, no help

Each one will run fine by itself, in its respective slot no less.

Do I need 2 SLI bridges perhaps? Or maybe try a different SLI bridge than the 1 I'm currently using?

The odd thing is that these 2 cards worked fine together in different configurations before.

Originally, on the corsair 750, both cards ran with stock coolers, then I ran 1 with an aio with a dwood bracket and the other with the stock cooler, SLI no problem.

This is very odd
 
If it worked at stock and doesn't work now, that would potentially indicate a short somewhere. That's my first thought. That doesn't sound like an issue inherent to SLI, could you have possibly damaged a trace or power connector in the process (which would cause a short?)?

That's the most plausible explanation for stock working, and it not working now.
 
But with each card working fine by itself, wouldn't I see some form of problem when running each card by itself?
 
Bios Reset - Nope
New SLI cable - Nope
One PSU per card - Nope

Any other ideas?
 
I did milch. That was one of the first things I did. Still nothing.

Since they work separately, I cannot fathom what the hell is wrong.
 
Don't bother with reinstalling the drivers, Nvida drivers are never the issue. They are godsend.
 
I had something similar to this happen recently. I took out my motherboard and PSU and then reinstalled them, which fixed the problem. Something must have been shorting once the second card was installed.
 
I really feel like, by the description, that a short is causing the issue. Shorts are extremely difficult to isolate, the last time I had one (complete with mysterious reboots at spontaneous times) the only way to fix it was to completely disassemble my PC and reassemble it. Towards the end I found a stray metal piece which was causing the short. This wasn't on the GPU BTW, it was on the motherboard. It would reboot at completely random times.

I dunno man. Such a strange problem - the cards worked with the stock cooler in SLI but suddenly don't work with the aftermarket coolers. Did you check the SLI connectors? Did you damage any traces on that part of the PCB on either card?
 
So after all my heartache yesterday, I unhooked everything and swapped the card positions. Problem solved.

I've no idea why that would make any difference at all, but it runs flawlessly now and OC's up to 1306 on both cards.

Strangest thing ever.
 
Glad to hear you fixed it. Always sucks when new toys don't work
 
[L]imey;1040608201 said:
So after all my heartache yesterday, I unhooked everything and swapped the card positions. Problem solved.

I've no idea why that would make any difference at all, but it runs flawlessly now and OC's up to 1306 on both cards.

Strangest thing ever.
Click to expand...

Y'know, I wish I had suggested this. I had the same damn problem with my 570's. They would only play nice if my MSI OC unit was installed on the top and the ref unit below. In the other order, the system would seemingly boot, but I could never get any video output.

Glad it's working now! :D
 
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