[Prestonzee]

I doubled the RAM my ASUS P5B-E was using by installing 2 Kingston KVR800D2N5/1G sticks (identical to first 2, except these were much smaller), from same vendor too. Now the strangest thing - I install a third stick, windows says I have 3 gigs. Install the 4th, windows says I have 4 gigs with 2.94 usable. Web page navigation is really choppy.
I decrease installed RAM by removing one stick, now windows says I have 3 gigs. So apparently I now have more RAM by using less RAM. So far web pag navigation seems to be smoother.
Well, that's good. But I really want to use all 4 gigs of RAM. I am using Win 7RC Ultimate. Any ideas?

[BG-0]

Motherboard northbridge is unable to handle the load of all memory slots being occupated for some reason. Swap to 2x2 GB of RAM if possible, or deal with having 3 GB.
FWIW, you may get better performance with just 2 GB installed, as you get dual channel. 2 GB is sufficient for basic use, and with dual channel your memory operates faster.