I wouldn't run a system with out thermal paste, your machine may run without it but I wouldn't personally.

I recommend http://www.aria.co.uk/Products/Compo...productId=7774

My system dropped 20 degrees celcius under full load using it compaired to

the standard stuff that came on my heatsink and fan.

It's only £4 and well worth it and should do about 100 cpu's