This is kind of weird

[heffer]

originally i had one stick of 256MB DDR400 RAM in my computer. and then i recently added a 512MB DDR400 RAM module in there beside it. But windows says it only sees 512MB, instead of 768MB. Second thing i tried was replace the memories sticks, and then my computer only read 256MB of physical memory instead of 768MB. but in both cases, "cpu-z" could read the 768MB no problem. so what's going on here?

Athlon 64 2800+
Asus K8V-MX mobo (2 RAM slots)

 

[brinks]

It's probably because of your integrated graphics. Since your adding more ram, your bios is automatically adjusting the amount of memory to use for the graphics.

Go into your bios and check out how much of it is being used for the graphics.

 

[heffer]

right now its not giving any memory to the integrated graphics. i'm using a dedicated video card (ATI Radeon 9250)

 

[plumber4578]

are one of your DIMM slots damaged and not reading that stick of RAM that you put in the particular slot??