After putting in new hardware my computer fan has been spinning faster.
Also, if i put my hand behind my tower it is very hot.

I dont know whats the matter.
I've cleaned it of dust multiple times and that does nothing.
Im wondering how to fix it.
I only really notice this when I would start a game on my computer, like when Im putting stress under it.
For example, I would start up World of Warcraft and the fan would gradually get louder and louder. Untill its at the point I cant take it and must turn off my comp or exit the program.
Another thing that happens is when I exit the program I get a blue screen error, but only when the fan is spinning loud.
Then, when I turn my computer off and turn it back on the fan is spinning like a bat out of hell for approx. 3 sec.
Can someone please tell me whats the matter, or what could be happening.
Should I just buy a new fan and replace this one?