random reboots can be caused by many things, PSU is a common culprit. However as you've just upgraded your CPU you're right to start your trouble shooting there.
For starters Is it working properly?:
All 4 cores show up?
Performance as expected?
Does the BIOS recognise the Chip model?
stable under benchmark (prime95)?
Also check your mobo manufacturer website for compatability/issues/BIOS upgrade... I'm sure you don't need someone to do that for you.