I have an AMD Athlon 64 x2 4400+(2.3GHz) overclocked to 2.7 GHz and 2Gb of DDR2 800MHz RAM overclocked to 900Mhz in single channel and halo 2 has been giving me lower frame rates at minimum settings and I know it's not the graphics card because even on maximum settings it gives me similar frame rates and my graphics card is not that bad I even overclocked it.
What do you think my bottleneck is?
CPU:AMD Athlon 64 x2 4400+ 2.3 GHz OC'ed to 2.7 GHz
RAM:Two 1GB sticks of DDR2 PC6400 800 MHz OC'ed to 900MHz single channel
GPU:Geforce 8500 GT 512Mb OC'ed
OS:Windows 7 Home P 64 bit
Halo 2 Vista requirements:
RAM:1GB(it actually ends up using almost if not all 2GB of my RAM because windows 7 64 bit minimum RAM requirement is 2GB)
GPU:Nvidia Geforce 6100 / Ati X700 or above
Move your ram so its in dual channel mode and see if that improves it at all. You probably want to go to a full 4GB of ram if you can, most things will appreciate it, and it should help your gaming a bit too.