Graphical Artifacting in HL games

[BaconIsGood4You]

After about 15 minutes of play I start to get graphical artifacts. The longer I play the more severe it becomes. Specifically I'm getting green and purple geometric shapes flickering on geometry. Some stuff will be fine, while others very bad.

I first noticed this when I played Minerva Ep3 and am getting the problem in Portal and Episode 2. I am not getting this issue in Team Fortress 2.

I've installed the latest video card driver and the latest DirectX. I've run the GCF validation for Portal and I had no issues.

My comp specs are
1 gig ram
Geforce 6600GT
P4 2.8 ghz
Windows XP Professional SP2



EDIT:
I think I found the problem. I opened my case and discovered that my video card fan had exploded. Literally, it was burned and dangling out of the card. I think it's been like that for a while actually. That and it was dirty as heck.

 

[Sabrewolfe]

Well, my video card is fine, but I've been having similar artifacting issues with Portal myself. It seems to be especially bad on the places where you can see under the main floor. I haven't tried Ep.2 yet to see if it does it as well. TF2 likewise runs fine for me.

System
Toshiba Satellite A215 series
AMD Turion 64x2 TL-52 (1.6GHz)
4GB PC2-5300/DDR2-667MHz RAM (3.45GB seen)
ATi Mobility Radeon X1200
Windows Vista Home Premium: up to date
Steam: up to date
Drivers: up to date
DirectX 10

 

[BaconIsGood4You]

After I cleaned out my computer the artifacting was much better. Instead of green/purple shapes now I'll occasionally get grayscale squares, much less distracting, that disappear when I reload my save.

If you haven't cleaned your computer (dust and stuff), I'd try that.