Shkipan :
WHen I change the resolution in game, I will be able to play for a few minutes but then I will inevitably crash again.If it helps you, I was using the card (GTX 660 ti) before and I had appcrashes all the time,but as I said..I have tested the ram almost 10 times.I'm still testing the video ram and no errors found so far.Other than that, I'm able to browse the internet with no problems.
Shkipan :
Well, the test is done and no errors were found.
Due to the fact that you've had 2 cards do the same thing, I'd say the issue is with your ram, motherboard or the OS.
Try your cards in a friend's system. I bet they're fine and will work.
If it were my system next steps would be:
1. Make sure the BIOS on the board is up to date.
3. Swap in different RAM, I know you tested it but the tests aren't always accurate. If you can't get a hold of known good ram, just ask a buddy if you could pop your ram into their system and try playing a game and see what happens. If your ram works in another system, then it's your install of windows that is buggered up, or the motherboard.
2. If you can eliminate the ram as the issue, reinstall windows.
3. If that doesn't fix it, it's likely the mobo.
Bottom line is that there's no better test of hardware than trying it in something else.
Quick question, what's your system specs? If they're in your sig I can't see them for some reason. Are you over clocking your Cpu? If so have you ran prime95 to see if the Cpu can handle it?