not seeing all available RAM

[Mïcrösöül°V³]

I have a shuttle MV43VN mobo to run my exchange server. I was wondering why it dont show the full amount of RAM in it. I have 2 256 sticks in it, and the computer properties shows 480 instead of 512. I have never seen this before, so maybe its common or something. All my other pc's show 512, 1gig, or whatever, but never an odd number like that. I had a 128 stick in it while testing it, and knoppix only read 88mb of it. Anyone have an idea about something I may have missed. So knoppix and windows wont read the full amount. There arent any jumpers on the board except for cpu clock and stuff like that. I think I posted everything that you may ask for. Oh, the bios does have settings, but Im not real sure what to set them to, so i just let the bios load the optimum settings itself. also, the sticks are both:
Kingston DDR 256/333
kvr333x64c25/256
if any of that helps at all

The only setting I see in the bios are:
DRAM Frequency (set at AUTO - with choices of 133mhz or 100mhz)
DRAM CAS# latency (set at 2.5)
DRAM Bank Interleave (disabled)

[clocker]

Are you running 32MB onboard video perchance?

Specifications: CPU Support: Intel Pentium 4, 478-pin processors with 400/533 MHz FSB. Chipset: Features VIA P4M266A N.B. and VIA VT8235 S.B.. Integrated Graphics Controller: P4M266A integrates S3 Savag4 TM graphics accelerator into a single chip. P4M266A brings mainstream graphics performance to the Value PC with leading-edge 2D, 3D and DVD video acceleration into a cost effective package. Based on its capabilities, P4M266A is an ideal solution for the consumer, corporate mobile users and entry-level professionals. Maximum-shared memory size is 32MB.

[Mïcrösöül°V³]

um, yes, the integrated video. I think I know where you are going with this

[clocker]

So I can stop now?

[mr. nails]

why would it do that? does that mean that he's not getting a full 512mb of ram performance or it's just not displaying?

[Mïcrösöül°V³]

Nah, it means the onboard video is using up around 32mb of the RAM, so I just put an AGP vid card in the slot, and got my RAM back. I need all I can get for running MS exchange. It never even dawned on me to check that. I got too much else to think of, so simple things just seem to slip on by