My CPU is overheating HELP!

Solution
Eh, makes sense. Stock cooler is sort of the bare minimum for cooling and I believe 90C is kind of extreme for intel and around the throttle range. If you're really concerned I'd look into aftermarket heatsinks.
Yes, if you have thermal throttling enabled the system will detect when the temperature gets too high, decrease power and CPU load until it's not a fireball anymore.

Is this an intel CPU? AMD?

If you don't know, look in dxdiag, core temp, hwmonitor, whatever you use.