I have build a new CPU with ASUS P8Z77V-LX, i5 3570k,4gb vengence, corsair 500W Builder Series and 500GB Seggate HDD. When I check the computer properties, the Windows 7 64bit edition shows only 3.70GB RAM as usable. Why is that so ?
I think the answer above solved it since there is no issue to start with. You can always look at what the BIOS reports to verify but really this is a non issue.
If you are using a discrete graphics card you can also activate the memory remap feature (which take the normal amount of RAM taken by your non-working integrated GPU and give it back to your RAM pool). If you are using the integrated GPU then you might not be able to do this.