Originally Posted by gard9070
could the fact that i dont have any thermal paste be the problem?
What excatly do you mean don't have any thermal paste? you should have a thin layer of thermal paste that lies between the CPU and the heatsink, yes if you don't have any thermal paste between the CPU and heatsink this will be the cause of the problem.
However most OEM heatsinks come with an already applied layer of thermal paste layered to the underside of the heatsink, although often this thermal paste is inadequate it shouldnt cause your pc to turn off after 30 mins, however you should still consider getting some artic silver thermal paste.
If when you take off your heatsink on the CPU and the CPU doesn't look something like this http://www.cpu-cooler-upgrade.co.uk/...mal-grease.jpg
but rather looks more like this http://www.techpowerup.com/reviews/Z.../zbtf92-29.jpg
then you need to get some thermal paste and this will solve your problem