High Ram usage and CPU spiking, long ordeal still ongoing

[PP Mguire]

If you have a copy of your OS just back up the things you don't want deleted, boot to your OS (DVD or USB Flash Drive), format, and do a fresh install.

 

[Pow3rful]

So, I am in the process of finding my cd for the fresh install and I noticed that my computer says i only have 4gb of installed memory. The problem with this is i have 6gb of ram in the computer... One of my sticks is dead? How can i check this?