XFX 8800GTX XXX - Problem=Drivers? Temps? PSU?

HELP

I started this issue here....http://forums.hexus.net/showthread.php?t=120559....but I think its more apliccable in this Forum.

See 'MySystem' for specs.

I have used 2 PSU check calculators including Asus' own and 750W should do my setup, so the 800W should not be the issue?

I have launched Vista out the Window (pardon the pun!) and reinstalled XP 64, using forceware 163.71 and nforce 9.53
To start off both GTXs are installed and linked but SLI is disabled in nControlPanel
Running 3Mark06 I get a score of 10293 with everything at stock no problem.
Enabling SLI - The system repeatedly fails on the SM3 Graphics Test when the chappies get the cannon flaps up, not always in exactly the same spot but there-abouts.
I checked the graphics temps at the end of each test prior to this and the cards dont get above 75

I dont want to go back to 32 bit as I will lose access to 1 of the 4Gb, but should I try this? Or is it a driver issue?

The only thing I note is the memory is not on Asus QVL list, but if it gets this far 'd have thought it be ok?

so vista and XP 64 bit dont like SLI on yours, have you not got a copy of good old xp 32 bit to throw on as thats best suited for gaming stability and compatability wise?

i know you dont want to, but cant you create a small partition to test the theory that both your OS are at fault?
otherwise it may be an impossible mission.

Quote:

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Originally Posted by GoNz0

so vista and XP 64 bit dont like SLI on yours, have you not got a copy of good old xp 32 bit to throw on as thats best suited for gaming stability and compatability wise?

i know you dont want to, but cant you create a small partition to test the theory that both your OS are at fault?
otherwise it may be an impossible mission.

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I am willing to try anything once! So long as it proves the PSU and temps are not the issue......

I take it the answer to 32bit XP or Vista 32 (I have both) is going to be:: XP is more stable?????

its been the mainstream for a few years, the 64 bit versions have never got the support of 32 bit, thats all im thinking with 32 bit XP

Just had a play around with a few settings....

GPU Fans set to direct control and on full - Still crashed
Underclocked GPUs to 625 - Still crashed

Underclocked GPUs to 600 and GPU Memory to 800 (stock was 630/1000) - 3DMark06 ran 1 pass successfully and returned a score of 11308.....

Makes me wonder if it is temps. Can't do anything about that today though - so will look at a larger case scenario with more airflow this next week....for now I will have to be content with adjusting to find the best stable clock settings....BUT I am amazed an overtemp crashes the whole system and not just a graphics hang......anyone had this before?

Thinking of trying the same with Vista ....but TBH dont think it gives a whole lot more...may hold that thought for SP1.....

Test each card by it self using 3D mark 06 and ATI tool and games, if each card comes back fine but only fails on SLI then I would think about RMA.