RockmasteR

Hello and welcome to TSF

400 to 500 FPS??
that's impossible, I think the best FPS for playing games is 60 fps, above that number its really meaningless, try to force the Vsync on from your Nvidia Forceware Control Panel
could you please specify your PSU brand, watts and Amps under the +12V
also download SIW from my sig and open it
under "Hardware" choose "Sensors" and check your temps
enter a game and play for about 20 to 30 mins
minimize it and recheck your temps again
post both of them here
Remember that having an FPS above your Screen Refresh Rate (eg: 80 hertz) will look like the game is stuttering it's called screen tearing
if you have a refresh rate of 80 the best thing your FPS should be is at 60 to 80 max
so that's why we use the Vertical Synchronization (V-Sync)