Ok, here's the go.
i have had this computer for 3months and programs work fine but ALL games (oblivion, battlefield 2, company of heroes, black & white 2) that i have all CTD (Crash to desktop) within 10mins .

I have tried everything i can possibly think of...
ram has been tested on two 24hour memtests (no errors watsoever!)

there are no heat issues (i have sensors hooked up to gpu/cpu/mb(nb+sb) ram and general case temp) <- these are third party external monitors not temperature from bios etc. there are no problems with temperature in bios etc either.

all drivers are completely up to date (also tried with drivers that came with parts)
windows xp is completely up to date. ive tried with and without antivirus (norton 2007). ive formatted my computer twice.

i have two hard drives, ive tried having windows on both (games are on same drive as windows)

games are all official copies, tried with latest patches and without (even though it happens with all games i have)

umm...

dxdiag no problems...

even updated my bios 2 weeks ago to the latest (p5n32sli se deluxe)

tried disabling my onboard sound card and using an additional sound card (xifi)

if im forgetting anything i've tried that too, ive tried all these things in different orders etc...

this is mind boggling me...

specs:
mob - P5N32SLI-SE-DELUXE
ram - Corsair XMS2 DDR2 800mhz (also tried running at 667mhz)
cpu - Core 2 E6600 2.4ghz 4mb
gpu - 1xnVidia Geforce 7950gt 512mb
(all with stock cooling) + 3 case fans (2x120mm 1x80mm)
snd - temporarily had a Xifi Fatal1ty
hdd - 2xSeagate 80gb 7200rpm sata2 (not in raid)
(all at stock speeds never altered upwards, ram was tried at 667mhz but is currently at 800mhz)
problem only occurs playing games, i use lightwave 3d which heavily uses the gpu and never had anyproblems with that.
Any help would be much apppreciated thanks...

also windows xp professional is what i use, but i have tried with windows xp home (both are official copies)

Do you get any error messages at all? to indicate what went wrong?