I just attempted to upgrade an old system I built years ago. Not much of a computer guy, but wanted to add some RAM. I installed 6 sticks of 4GB. In BIOS, it shows physical memory at 24576MB, Cache size of 1024KB and L3 Cache size of 8192KB. Under Device Specs, I show 24GB RAM installed and only 2.99GB usable. I have reinstalled to the sticks to no avail. I am using these sticks as they show to have been compatible on the MSI site. Where do I go from here?