DDR2 RAM 1GB uses only 512MB

[Scarabey]

Hi, I have a problem with my RAM, so I have 1GB DDR2 SDRAM, but PC uses only half of it. SO in BIOS I can change RAM's clock from default 200MHz to 266MHz, but RAM is PC2-6400 400MHz. What I can or have to do, to use full RAM?? Photos attached from CPU-Z info. I run Windows XP SP3, but Windows 7 shows me the same.

 

[Cycloid Torus]

Confirm the memory you are using is on motherboard's QVL (qualified vendor list) for your BIOS version. This list is in the manual and may be on the motherboard maker's website.