yep could be an installation issue. GTA4 should not lag on your system since youre on a quad. and SF4 most certainly shouldnt. try a fresh reinstall. and try a different crack after the reinstall as well.
Strange. Both the games shouldnt lag on your rig at all, especially SF4. Did you try lowering the settings and the res down to the lowest? Check if that makes a difference. Check if your card is running at full 16x in the BIOS. Also run a virus scan, CPU and RAM usage can increase if you have malware in your system.
thats great....firstly update to latet driver and u can check load temps fan speed and control it etc etc from the overdrive tab in the new catalyst control centre
for benchmarking use 3dmark vantage (find with serials) and unengine heaven benchmarking......heaven will show u what dx11 can realy do