Visual Issues on Valve Source Games

[CrispexOps]

Hey everyone, when I first bought my PC I bought a ATI Radeon 5450 HD, it's good with most games, but usually you have to run them on low settings because that card is made for media boxes. So the other day I bought an Nvidia GeForce 8800 GTX, it came today, I popped it in, and I noticed that when I start playing ANY Source game, the menus and loading screens work, but then after only a few seconds of play, things get distorted and start acting up. I've tried the card on:

Team Fortress 2
Garry's Mod
Left 4 Dead
Left 4 Dead 2
Half-Life 2 (Plus Episodes.)
Counter-Strike: Source

Here are a few screenshots of what I see:

http://img202.imageshack.us/g/issue1.png/

It can't be the card becuase it plays Call of Duty 4 and Battlefield 2 properly.

Here are my system specs:

Processor: AMD Athlon II x2 250 3.0 GHz
RAM: 4gb DDR3
Hard Drive 7200 RPM Western Digital 320gb
PSU: 450 Watt PSU 12v
GPU: Nvidia GeForce 8800 GTX
Operating System: Windows 7 64 bit edition.

This isn't happening for any other game, really. The card is in the slot the full way, all the cables are connected appropriately, and I've got the most recent drivers for it. Most games are set to the "High" setting, I disabled Anti-Aliasing, and they even do this on low settings too. The games worked fine on my other card.

I've also tried re-inserting the card, replugging in the power cords, resetting to the default settings for the games, re-installing drivers / using old drivers, nothing seems to be working.

Any help?

 

[rolli59]

Try enabling Vsync when playing those games, looks like screen tearing to me.

 

[CrispexOps]

Screen tearing would cause it to turn eventually black the whole way?

Update: I turned it on, and it's still giving me the visual issues.