Alright, that's a respectable machine and you shouldn't be having any problems running the games you've mentioned.
Far Cry 1 will run on more or less anything but Far Cry 2 did cause a few minor problems on release.
I presume you've uninstalled - or attempted to - any games you suspected of causing the problem? Have you deleted their respective folders from Program Files? That would be a good idea. And I assume everything was running ok before one or more games were installed.
Here's a link to your motherboard spec:
http://www.biostar.com.tw/app/en/mb/...n.php?S_ID=455
It has onboard graphics, are these disabled in the BIOS cos if they're not that would certainly cause a few glitches.
Have you had a look through my BSOD thread including the link to another place to see if there's anything there to help you?