vista 64bit rc2 not seeing 4gig pc2-5300

i thought it will read or is it a component that i've overlooked? vista performance shows me as a 64bit system. any thoughts?

ASUS P5LD2 rev A2
Prescott 541 [email protected]
4096 MB(PC2-5300) @ 5-5-5-14
4x hdd raid 0
X-FI Extreme Music @ 5.1
XFX 7600GT [620/1550 oc'd]
soyo 32" hdtv 1366x768 720p res

My friend is experiencing the same thing. I am not sure why as yet.

EDIT: however he is running 6 gigs of ram and it doesn't see the last gig.

Check to see if a BIOS update is available, and then check in the BIOS for a MTRR setting. If the setting is available, then set it to Discrete... and not the default of Continuous. The MTRR setting is usually found in the Advanced - CPU configuration BIOS settings, but the setting may not be available with your particular BIOS.

Check out these two sites for some background info on the MTRR setting...

MTRR (Memory Type Range Registers)
http://en.wikipedia.org/wiki/MTRR

http://www.planetamd64.com/index.php?showtopic=16222