Both of my 7900GT's work fine by them selves but not in SLI WHY?

No because when I built the machine I downloaded it and tried to run it but it crashed the machine before it would load. I asumed it is was incompatible with windows x64 so I havent tried since.

 

From what I've read it is my opinion that it is a mobo problem NOT a card related problem, but I am no expert.

 

I personally think it could be a combination of both.

 

Ok now we're getting somewhere!
To confirm, run a game - you have the fuzzy screen. Alt tab out and back in and the game's then fine. However when a new level is loaded, you get the fuzzy screen again and you have to alt/tab out to correct it?

<edit> what drivers are you running mate </edit>

<edit #2> Ok, latest drivers for XP64 are 91.47's. Change the drivers mate, roll back to an earlier version if you can. *should* solve the problem </edit #2>

<edit #3> http://www.nvidia.com/object/winxp64_91.31.html are the next newest XP64 drivers. Give them a shot and see if they solve the issue. It's worth removing the current drivers first, drivercleaner them perhaps. If you're not using XP64 (previous post seemed to suggest you were) then you'll need other drivers </edit #3>

 

I think that XP64s game support is terrific either, there may be a problem with the games you are running and the compatibility layer. I would strongly reccomend you use 32 bit or if you really want 64 bit go for Vista.

 

Before I start messing with the drivers I did have 91.31 installed and I have had the same problem. Is it work me putting old driers on?

 

frombrowsing t'interwibble it seems a fair few people had problems with the x.47 drivers. Showed similar issues to those you have.
Also some users had issues wth all the 9x.xx drivers and asus boards. With this in mind it might be worth trying older drivers.

 

Ok Ill give it a go thanks

 

Tried the older drivers no change.

 

possibly a board BIOS setting is wrong.

Possibly the drivers...make sure the old ones are totally removed before trying old ones

I`m guessing nv drivers are advanced enough to get around the possiblility of different GPU BIOS?

Kenny

 

Are there any specific options in the BIOS that should be enabled?

 

I've just installed the latest drivers for the GFX cards and it seems to have resolved the origional problem however I am getting poor performance. In the COH performance test with the settings on Automatic I get 11FPS this is way way under what I expect from a rig like mine. Any ideas on improving things?

 

Do you have the amd drivers and dual core optimizer loaded? I have a similar system to your self (well 7900GTo but theres not much between them) and had no issues with 91.31 and CoH in XP64

 

Sory for the late response I have installed the latest drivers and it has had no effect

 

I had a similar problem with my old motherboard, where SiSoft Sandra just crashed the whole machine any time you tried to run a test. Turns out my motherboard was faulty, and now I have a new one, everything's great...
Not sure if it's the same problem, but it could probably account for all your problems that you're having.

 

Is there any way I can confirm that my motherboard is faulty so I can RMA it as I dont have any evidence that its faulty.

 

Not that I know of. I sent mine back because I had tried everything else.