Do I have to restart my computer for it to take effect? Yesterday I cranked up my FSB way too high and the computer just restarted. Does that mean the change is instant? But when I go to system settings it says my CPU is at 2.6 GHz when CPUCool says it's at 3.0 GHz.. I'm so confused.

What does your BIOS report for your CPU's core frequency and FSB frequency compared to "CPUCool"?

I'm not familiar with the software myself, but, if your BIOS supports overclocking I would honestly ditch any third party software and make your changes via the BIOS.

My BIOS doesn't support overclocking. When I set my CPU to 3.0 and restart, everything says 3.0 but as soon as i restart again, it changes back to 2.6. I don't want to restart my computer every time I want to play a game.

...Well, it's either caused by some form of incompatibility between the third party software and your PC or, your system just can't handle that large of an overclock. Both are pretty possible. Try taking it a bit slower, perhaps 10 MHz at a time.