HELP I keep getting blue screens 7850hd

[Super6eighT]

Hi guys and gals,
I'm running 2 radeon HD7850s cross fired and the one running my monitor gets different hashrates on the same settings as the other one. It also craps out on me around 74 degrees Celsius. I get a blue screen or grey screen or something that stops displaying my desktop. They are both in the same tower and I'm getting around 325 kh/s for both of them. I think it's overheating... What's a good operating temperature for these and how can I stabilize the temperatures for both? I'm running an old monitor using a dvi to vga adapter. Also, strangely enough, if I change the monitor to the other card, suddenly the one that keeps crapping out on me gets 30kh/s without changing the settings!?!? I'm so confused...  I'm running cgminer 3.7.2. Here is my coding
 --thread-concurrency 8000 -I 13 -g 1
THAT'S IT!!
I don't know what to do.. I got the cards off of Craigslist so maybe one of them was faulty...
PLZ HELP  I really want to keep the longevity of the cards high so I don't want them too hot or to put to much strain on them. Again, I am happy with 325 kh/s...  Running windows 7 ultimate 64 bit as well. 
Thank you!!!

[1715112894]

1715112894

[1715112894]

1715112894

[smoke187]

Hi

I had some similar issues with my screen going blank from time to time, but mine was like every 24H
What helped me was, using the 13.12 drivers, but I did not install the AMD/ATI Catalyst software, I just installed the drivers by selecting my windows device manager and finding my display adapter and updating the drivers and selected my drivers manually.

I still have some crashes from time to time, but not as frequent as before.

I'm still a noob at mining, but finding out how to fix my problems as I go along.