Odd RAM problem, or is this normal?

[pjkeyzer]

I just installed the Windows 7 RC 64bit, and decided to go from 2gb of RAM to 6gb. I had 2x1gb, and added 2x2gb. The thing I'm experiencing is that with both of the 2gb sticks installed at the same time, the system recognizes 1gb less that whatever is installed. IE, if I install all 6gb, the POST screen shows 5056mb, and Windows says I have 6gb with 4.94 available. Both 2gb sticks only will show in windows as 4gb with 2.94 available. I can boot with either one of the 2gb sticks on its own, and it will show the full 2gb. Is this normal for it to subtract 1gb above a certain amount? I would expect something like this with 32bit and the 3gb limit, but not 64bit. Any ideas?

Specs:
Asus P5B-e
Intel Core 2 Duo E6600
6gb g.skill DDR2-800 (2x1gb, 2x2gb)
EVGA GeForce 8800 GTS 640mb
2x320gb Seagate SATA drives in RAID
old failing 80gb IDE drive (I should take that out sometime)
600Watt Seasonic PSU
Windows 7 RC1 64bit

 

[setscrew]

You might want to bump up the northbridge voltage a tad as you are populating all DIMM slots.

Does BIOS recognize the DIMMs properly?