The CPU has a large impact on games, some more then others. The CPU will handle AI calculations, physics, and other such maths. It will also handle any graphics off-loaded by the GPU. If your CPU is underpowered it will bottleneck the GPU and slow everthing down.
Consolt your user manual for step by step instructions. It's not really hard to do, but you want to make sure you do it right. The BIOS that is shipped with the motherboard is pre-installed but it's probably out dated.
If you don't have the manual it can be found on the Asus website link I gave you.
If your pc is just shutting off and restarting when you're putting a significant load on it, it could be your power supply. PSU's degrade over time and if you have a cheap one then this could certainly be the issue.
ok i have noticed instead od restarting like it did on the old mobo it now says atleast 100% of atleast 1 cpu being used.Then not to long after that instead of restarting now it freezes.And I have to restart it myself.ctrl-alt-delt does even work once it freezes