[Solved] How to access all ram on my system

[kricha59]

My computer is a home build machine Mobo is MSI, cpu is an AMD Athlon 7750 2.71GHz 140 GB hard drive for systems only and 5 TB of storage. Running Vista 64 Home Premium. I started out with two 1 GB ram mods. When I tried to upgrade ram with two 2 GB mods the system only show 2 GB of ram not 4 GB. What can I do to get it to find all ram? I have switched the mods between slots. Removed and reinstalled. Put them in other computers to find out if they work (which they do). Just don't know what to try next. If you need more infro let me know.

 

[rgd1101]

not show on bios or windows?