7800GT(515) question

[Dunkler Vagabund]

ok, as you can see from my signature i am running an evga 7800gt(the 515 model 445core/1070mem). I overclocked this thing to 500core/1200mem and it handled 3dmark05, fable, aom, farcry and so on just fine, with no artifacting or odd colors. Well, i downloaded an open source game engine from Garage games called Torque and when i ran the demo of what it can do, i had some artifacting. So i lowered my speeds back down and it stopped. Also when running 3d Studio max 5 i had some weird colors at the overclocked speeds... my question is why does it do this on those 2 things at oc speed and not the other games and 3dmark05. Any ideas? my temps seem to be stable around 53 degrees celcius under load.