Ok, I'm using windows for the games, but still it's a problem.
I've just dusted the PC and cleared the fans and vents when I fitted 2 new hard drives. I find it crashes playing Fallout New Vegas and Batman Arkham Asylum after a few minutes, but can play angry birds for hours.
I know fallout is unstable, but I never had a problem with Batman before.
I suspect it's a problem with my graphics card, but could do with advice.
Oh, and Linux doesn't crash!
i5 4440 3.1Ghz, Asus H87M-E motherboard, 8GB DDR3, 2GB DDR5 nVidia card, 2x500GB Seagate hd, Coolermaster 750W PSU running Mint 17.1 MATE and Win7
HP mini, 1.66 Ghz Intel atom processor, 2 GB DDR3, 320 GB hd, Mint 17 MATE