That'll keep you busy.
Fallout 3 and NV plus both the Mass Effect games are great but you need to invest the time.
Is that the original Deus Ex you've listed?
Crysis/Warhead/2, Metro 2033, Just Cause 2... all a must for their eye candy.
Bioshock, Borderlands, Company of Heroes, Battlefield Bad Company 2, Starcraft 2, Batman AA... there are too many to name really, it's definitely worth going through the back catalogue of highly rated games. I spent my first couple of years of PC gaming doing this.
Could be that the CPU heatsink's come loose. They can be a real pain in the arse to get seated properly, if it's come loose the CPU could be instantly overheating and causing you poota to shut off.
If that's not the case, like one of the other guys said, reseat everything, reset the CMOS by moving one of the jumpers on the board or removing the battery (should be a diagram in the mobo manual).
I reckon it's a BIOS issue.