I don't know why but for some reason, my computer can't run most games as good anymore. For example when I played Unturned, it originally ran on 30fps with lowest settings, but now it's 10fps. I made sure nothing was running in the background and my games still lagged. Anyone knows what causes FPS drops?

BTW My processor is Intel Pentium CPU B950 @ 2.10GHz

UPDATE: Nevermind. I figured out the problem. Turns out it was because in the settings, I made my fan sound set to "low." I had to set it to "off" to get rid of the bad performance.