I wasn't 100% sure where to ask this, so I'll drop it here

My computer for the past few months has had the fan running noticeably more often that it used to. Also, I can't play the games I used to be able to due to poor performance, which I figure is due to the system underclocking(?) the CPU and GPU to cool it down. I took everything apart and cleaned but it didn't help with the temperature at all. I've also looked into updating all my drivers but they are all up-to-date. I don't think its a problem with the fan because I hear it running all the time and I still feel air coming out the vents, so I couldn't imagine there being a clog anywhere.

My CPU is a Intel i5 2450, and my GPU is a Intel HD Graphics 3000. Its not exactly a gaming rig but it used to be able to run my games with ease, and now it can't even start them without my entire computer shutting off due to heat. At this point I'm just kind of at a loss of what I should do