Wierd SLI issues. Advice appreciated.

[Puck Nutty]

Ok, so I have 2 8800GTs in SLI mode and I admit to being a bit of a noob when it comes to SLI. The basic problem is that whenever I try to play a game, my whole system will freeze after a few minutes of playing. If I disable SLI mode through the Nvidia control panel, everything is fine, I can game as long as I want.

Device Manager lists the 2 cards as functioning properly, and I have up to date drivers as of this posting. I ran memtest86 version 3.4 and no errors were reported. I'm not really sure what else I can do to trouble-shoot the problem. Any advice is greatly appreciated.

My rig:
Q6700 2.6 Ghz Quad CPU
2 X Geforce 8800 GTs
4 X 1 GB Corsair DRAM
Soundblaster X-Fi soundcard
Asus P5N-E SLI mobo
Vista (32 Bit) fully updated

Thanx.

 

[bluntside]

Not saying that this might be the problem, but are both GPU running @ same frequencies?
Another possibility is that the bridge that is used to connect both GPU's is faulty or there can be a setting in the BIOS of your MOBO

 

[theblade]

Two cards produce more heat than one, what are your GPU temps?, does your case has proper air flow?
Also, what PSU do yuo have?
Try using only one card, then only the other card to make sure they are ok.

 

[Puck Nutty]

Not saying that this might be the problem, but are both GPU running @ same frequencies?
Another possibility is that the bridge that is used to connect both GPU's is faulty or there can be a setting in the BIOS of your MOBO

I didn't fiddle with any BIOS settings that weren't absolutely necessary when I assembled the rig in the first place, so everything should be set at default.

I assume the GPU freqs are indicated somewhere in the BIOS, yes?

I don't have another bridge handy, so ruling that out could be tricky.

Edit: Ok, so according to the app I just downloaded (GPU-z) one card is running at 650 Mhz and the other is running at 600 Mhz. The memory is also apparently running at different frequencies, as well. This is under idle conditions, of course. All I have running right now is my web browser.

 

[Puck Nutty]

Two cards produce more heat than one, what are your GPU temps?, does your case has proper air flow?
Also, what PSU do yuo have?
Try using only one card, then only the other card to make sure they are ok.

The only temps I can see in my BIOS right now are my CPU temp and the overall system temp. They both tend to range from 38 - 42C.

I'm using a 750XT Corsair PSU.

Thanks for the suggestion about swapping out the cards individually. I should have thought of that myself.

Edit: I just downloaded GPU-z and it says my GPUs idle at 44C. I'll try playing some TF2 and see what does to my temps.

Again, thanx to anyone who is willing to help me out.

 

[invisik]

I believe theirs your problem both card running different frequency could lead to instability. Try to clock same speeds on core shader and memory.

 

[Puck Nutty]

I believe theirs your problem both card running different frequency could lead to instability. Try to clock same speeds on core shader and memory.

Uh, ok. How do I do that?

As I said, I didn't make any changes to my BIOS when I built the rig. I just put everything together and fired it up.

The Nvidia control panel doesn't provide any options for changing clock speeds or anything like that, so I'm not sure where I should look. Device manager, maybe?

 

[invisik]

Download evga precision or rivatuner which should let you change clock speed.

 

[Puck Nutty]

Ok, well, I installed EVGA Precision and synched up the two cards frequencies, but it didn't help. I fired up the FEAR 2 demo, and my system locked up after about 1 minute of game time.

My GPU temps seem to top out at about 48C under load. I cranked up the fan speed on the cards as well, just to be safe.

Well, thanx anyway, invisik.

 

[xyzionz]

Try reduce the core speed of both cards to 600 from the overclocked one and memory speed to around 1500~1600

if problem still there, try removing ur 1st card and use ur 2nd card to test without the 1st card, if the 2nd card hangs try reducing the speed as well

even if u reduced the speed and the problem is still there, i guess u will need a RMA for that card

 

[xyzionz]

ops and remember to plug ur 2nd card to the 1st PCI-E slot for testing