Okay, so I'm pretty sure my PC should be able to run games such as Starcraft II and Portal 1, Half-Life 2, and the Source engine in general, and they run excellent for a few minutes, then they become unbearably laggy. I've tried changing the video settings to the absolute lowest possible, but that same thing keeps happening; it doesn't even lengthen the amount of time I play before it becomes laggy. So does anyone know what the problem could be?
System Specs
AMD Athlon(tm) II X4 620 Processor 2.60 GHz
6.00 GB (5.75 GB usable) RAM
64-bit Windows 7
GeForce 9100
Driver version: 270.61
DirectX support: 10
CUDA Cores: 8
Graphics clock: 500 MHz
Processor clock: 1200 MHz
Memory clock: 400 MHz (800 MHz data rate)
Memory interface: 64-bit
Total available graphics: 2943 MB
Dedicated video memory: 256 MB DDR2
System video memory: 0 MB
Shared system memory: 2687 MB
Video BIOS version: 62.77.2F.00.06
IRQ: 23
Bus: FPCI
System Specs
AMD Athlon(tm) II X4 620 Processor 2.60 GHz
6.00 GB (5.75 GB usable) RAM
64-bit Windows 7
GeForce 9100
Driver version: 270.61
DirectX support: 10
CUDA Cores: 8
Graphics clock: 500 MHz
Processor clock: 1200 MHz
Memory clock: 400 MHz (800 MHz data rate)
Memory interface: 64-bit
Total available graphics: 2943 MB
Dedicated video memory: 256 MB DDR2
System video memory: 0 MB
Shared system memory: 2687 MB
Video BIOS version: 62.77.2F.00.06
IRQ: 23
Bus: FPCI