Help! 6950 Xfire setup reboots PC within 2 min of gaming

NTAC

Senior member
May 21, 2003
391
1
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Hi guys,

Just got my 6950 cards, hooked them up but when I'm in crossfire mode the two games I've tried so far, Deus Ex HR and BF3, will reboot the system after about 1 or 2 min of game play.

This is my setup:

CPU: i5 750 @ 2.66 (NOT oclocked at the moment)
Cooler: Noctua NH-D14
Memory: 4GB
PSU: OCZGXS700(700W) - http://www.newegg.com/Product/Produc...82E16817341002
GPU: 2x Saphire Dirt 3 edition 6950 (stock spd and bios)
GPU Driver: 11.9
MOBO: ASUS P7P55D Deluxe
OS: Win Home Premium 7 64 Bit

What I've tried:
1. Disabled Crossfire (through Catalyst) which works fine, a single card has no problems.
2. Swapped the cards (moved card 1 to slot 2 and card 2 to slot 1), still works fine in NON crossfire mode, so at lest each card on its own is not causing any problems
3. Used GPUZ to check temps, nothing over 60ish Celsius.

I'm pretty much at a loss of what to do next, should I try the other Crossfire cable that came with my cards? I haven't done that yet.

Is 700W enough? I only have a single HD in the system, nothing else except for what I've listed above, oh well, I guess one standard DVD RW drive, nothing special.

Could I be connecting the wrong 6 pin connectors to the cards? I have like 6 of these things coming from the PSU, so I'm not sure if I'm doing something wrong there... Any help with that would be awesome!

Anyway, please let me know if you need more info from me, I'll be happy to provide.

Thanks!!
 
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badb0y

Diamond Member
Feb 22, 2010
4,015
30
91
It might be a PSU problem but before jumping to conclusions I would do the following:
Install DriverSweeper
Uninstall AMD drivers
Reboot into SafeMode(Optional)
Run Driversweeper
Reboot into Windows
Install latest drivers from AMD site with updated CAPs
Try to play games

If there is still a problem I would assume it's the PSU since the cards work fine on their own.
 
Feb 19, 2009
10,457
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Your PSU has 4x 12V rails 18A each, make sure you connect separate 6 pin plugs to each card and they don't share the rails.
 

Elfear

Diamond Member
May 30, 2004
7,096
640
126
I'll bet it's the PSU. With both of my cards running at 900/1350 I got occasional shutdowns with a quality 800W PSU. I never pulled more than 770W from the wallplate but maybe the 12V line feeding the cards was getting overwhelmed. Your OCZ PSU is decent but not what most consider high quality. Apparently the ripple is out of spec.

Do you have any buddies with a stout PSU you could borrow?
 

Wuzup101

Platinum Member
Feb 20, 2002
2,334
37
91
I'll bet it's the PSU. With both of my cards running at 900/1350 I got occasional shutdowns with a quality 800W PSU. I never pulled more than 770W from the wallplate but maybe the 12V line feeding the cards was getting overwhelmed. Your OCZ PSU is decent but not what most consider high quality. Apparently the ripple is out of spec.

Do you have any buddies with a stout PSU you could borrow?

Having a similar system, I would completely agree with the above. I have yet to see a problem with my corsair 750 watter; however, I know I'm on the cusp of what it can put out. I did some brieft testing a while back and I know that I can pull just shy of 700 watts from the wall while maxing my graphics cards and CPU at the same time (testing was done running prime and furmark at the same time).

I would try the troubleshooting above; however, it does seem like a PSU issue (either you need something with more power, or you need to rearrange your rail distribution (if that's even possible given the PSU setup - mine is single rail).
 

pw38

Senior member
Apr 21, 2010
294
0
0
I was thinking about trying X-fire again with another 6950 but with my PSU I think I'm going to stick to a single card for now. If I do I'm going to just go with a higher-end PSu (1000+) just to be safe.
 

NTAC

Senior member
May 21, 2003
391
1
0
Thanks guys you are all awesome!

The problem is fixed, I was not using the correct 6 pin for the second Video Card. Pretty silly of me, it is clearly labeled PCIe 2, but it was jammed underneath part of the case so I never saw it.

Anyway, played for 2 hours last night and the game runs like butter on Ultra with everything maxed out.

Thanks!!!
 

3DVagabond

Lifer
Aug 10, 2009
11,951
204
106
Thanks guys you are all awesome!

The problem is fixed, I was not using the correct 6 pin for the second Video Card. Pretty silly of me, it is clearly labeled PCIe 2, but it was jammed underneath part of the case so I never saw it.

Anyway, played for 2 hours last night and the game runs like butter on Ultra with everything maxed out.

Thanks!!!

Glad to see that you found the issue. Your PSU should be acceptable, not optimum, but acceptable. Unless it was defective, or OCZ is dropping the ball. I read a lot of bad ink from people about OCZ, in general. Even their PSU's, and they should be nothing short of fantastic.
 

NTAC

Senior member
May 21, 2003
391
1
0
Glad to see that you found the issue. Your PSU should be acceptable, not optimum, but acceptable. Unless it was defective, or OCZ is dropping the ball. I read a lot of bad ink from people about OCZ, in general. Even their PSU's, and they should be nothing short of fantastic.

I made sure to read lots of reviews back when I got this, and I don't knwo about the rest of OCZ stuff, but most reviews where pretty high on this PSU, and so far it has delivered, so hopefully it continues to do so.

After spending the money on those video cards I don't think I could've afforded a PSU upgrade as well, so I'm glad it works, for now at least.
 

NTAC

Senior member
May 21, 2003
391
1
0
Heh, tried to oclock back to 3.7... that didn't work out so hot.

So if I want to o clock again I will eventually need to upgrade the PSU.
 

NTAC

Senior member
May 21, 2003
391
1
0
Does it matter where the second 6 pin connectors for each video card come from?

I'm still trying to make sure I have it all setup as well as it can be...
 

Stuka87

Diamond Member
Dec 10, 2010
6,240
2,559
136
That PSU has 4 12V rails at only 18A each and 18A per rail is pretty marginal. And if the PCI-E plugs come from the same rail, well there you go.

Glad you got it working.
 
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NTAC

Senior member
May 21, 2003
391
1
0
That PSU has 4 12V rails at only 18A each and 18A per rail is pretty marginal. And if the PCI-E plugs come from the same rail, well there you go.

Glad you got it working.

So I still don't understand the rails thing and how to tell what I'm connecting, I guess I'm being a bit dense here.

So I have one PCI-E plug that says PCIe 1 on it, and it is its own wire coming straight out of the PSU with no branching cables off of it.... I plugged that into the first video card.

Then I have another wire just like this one, labeled PCIe 2 and I plugged that into the 2nd card.

So I think that so far I'm doing things correctly.

Now from this point I'm a little lost. Obviously I need to plug in two more 6 pin connectors, one for each card, and I'm not sure if it matters where those come from. I have probably at least 4 more lying around that are branched off some other wires, but I have no clue as to which one I should be using, or if it even matters at this point.
 

Elfear

Diamond Member
May 30, 2004
7,096
640
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There should be a diagram somewhere in your PSU manual or possibly on the box that shows which cables go to which rails. Usually the graphics cards have a rail or two to themselves depending on the PSU. Some PSU's are labeled as multi-rail but really feed off one big 12V line.