What is causing my server load to spike?
I'm a novice, so please be patient with me
I have a dual xeon dedicated server with Redhat Enterprise 3, CPanel, and WHM running some vbulletin forums.
98% of the time it runs great with a server load of around .30-.50. However, every now and then it spikes to 2.00 - 4.00. There isn't a substantial change in users on the forums or anything, just a spike out of nowhere.
What is the best way for me to find exactly what is using all of the CPU power?
Thank you kindly for any help.

