Stress Testing Multiple GPU's Simultaneously

Hey all!

I am looking for your input on the best way to simultaneously test a pair of 4850's.
I have been having occasional random crashes while gaming/folding over the past few months and have had some difficulties tracking down the cause.
All components test fine individually which leads me to believe the issues only arise when every component is being loaded fairly heavily.

I have been testing my GPU's one at a time with ATI Tool while running prime95 in the background.
As I have a display attached to each GPU, it is no trouble to switch a card to primary and individually test it in this method.
I have tried to add the '-gpu0' and '-gpu1' switch to a pair of shortcuts to no avail.
If anyone has any suggestions on how to get dual instances running, one for each GPU, please let me know.

Also, if anyone has any suggestions on other testing apps, feel free to suggest them.
Unfortunately my trusty old RaptorX bit the dust over the weekend and took my cache of testing software with it :(

My full system specs can be found in my profile.
Here are the most important parts:

Q6600 @ 3.2Ghz
6Gb DDR2 1066 5-5-5-18
Corsair 1000HX
2x 4850 512Mb's overclocked to 690/1100Mhz through a BIOS flash, brought back down to 625/995 with the CCC.
All drivers are up to date.

Any and all ideas are welcome!

Thanks for reading