I need help!!!!

My computer is about 6 months old. Here Are my specs

ASRock K8 Upgrade-1689 MoBo
AMD Sempron 2600+
ATI All-in-Wonder Radeon 9800 pro 128MB
768MB RAM
Hitachi 120GB HD
Windows XP Pro

Right then, my problem. Most of the games I run will play for a few minutes, then freeze. The computer makes some clicking noises, then I get a blank blue screen. I did have a WD 80GB HD that I thought was the problem. That got replaced by the Hitachi. I have also tried reinstalling windows, updating the bios, using Microsoft ATI drivers, using current and older ATI drivers, using current and older Omega ATI drivers(i figured cause it was games that it might have something to do with the graphics card), I've even tried different IDE cables and a new power supply . Please, anyone with any idea of what this could be let me know.

Cheers!!

it is probably a memory problem.

to start off with, you have 2 (or possibly 3) unmatched RAM sticks, which is probably where your problem lies. Remove all but 1 RAM stick and see if it still crashes.

give us your RAM configuration (i.e. 1x512MB + 1x256MB -or- 3x256MB, etc.) and your exact RAM specs (brand name, model #, speed, CAS/timing of each RAM stick)