Major issues with 5770 crossfire

[conorgray]

Ok so basically

I have a machine that runs a
EX58-UD3R motherboard equipped with
intel i7 2.66 GHz processor,
8GB DDR3 1333 RAM,
 a 750W power supply,
2 Gigabyte ati Radeon HD5770 graphics cards in crossfire,
1.5TB samsung Hard drive.

I origionally ran the system with just 1 5770 and it ran brilliantly. But when i got the second 5770 it worked in Crossfire for 2 days then stopped. I would get the occasional black flash on the screen and if i put any stress on them at all it would just go black. I RMA'd 1 of the cards as it was seemed faulty, but now that i have 2 WORKING cards i am still having problems.

I have tried installing the gigabyte driver and the ATI drivers.

I tried to update the BIOS but i get an error each time saying it's not the right 1 for my version of windows - but it doesn't give me the choice to chose which version of windows i am using.

Could really do with some help 

[Dark Mantis]

When you say yoiu tried to update the BIOS but it was the wrong version of Windows I don't understand. The BIOS is not Windows related. You have to have the correct version for your motherboard but thats all.

I think your graphics problem could either be insufficient power or an overheating problem.

[conorgray]

Ye one of the cards seems to get VERY hot, whereas the other is alright - the case is very well ventlilated though. The BIOS was the correct one - it was GA-EX58-UD3R (rev1.6) - which is what my board is.

Il try a larger power supply in it and get back to you.

[Dark Mantis]

It sounds like there isn't enough room between the graphics cards for one of them to draw in enough fresh air to cool the card sufficiently. I would hazzard a guess that it's the top card that is getting too hot, is that right?
 
I was considering what you said about updating the BIOS and Windows being the wrong version. Were you trying to do the update through Windows? If so DONT! You have much more of a possibility of bricking your motherboard as everyone knows(I thought) Use Q-Flash by pressing "End" when booting.

[conorgray]

Ye it is the top 1 - the 2 cards are both HD5770's but slightly different models and beacuse of this they only fit in that way , also Thanks for the tip on the BIOS also - i should've known this

[Dark Mantis]

The problem really lies with your use of two graphics cards on this board. THere are only two PCIe slots so you do not have the option of moving the cards away from each other hence the bottom card restricts the cooling airflow to the top card.