Videos, Flash, Games Lagg

OK I have install a new power supply motherboard RAM CPU graphics card I lag sometimes with on-line video sites like you-tube but when i download a video and play on full screen it works find and same with games it laggs majorly where it shoulnt lagg at all i never used cpu cooling paste before and thats the only thing I think i'm missing could not having that cause any of these problems

it's an intet

If your CPU fans heatsink is not flat and your CPU is not flat, not having thermal paste will cause it to get very hot.

Even if they were both near perfectly flat you need the thermal paste to ensure that the tiny grooves are filled and the heat is properly transfered from the CPU to the heatsink.

It seems like thats your problem, that your CPU is getting too hot. Hve a clue what your CPU temps are running at while doing this?