DDR 667 (2gig usable) what is the meaning of this?

[kevinniigaki]

I have 2gig of ram on my pc, and then I added up another 2gig of ram. it added up on system properties but there is a message says 2gig usable... what is the meaning of this? 2gig usable... the performance didn't change also in gaming.(^_^) plase help. how to solve my problem.

 

[marcellis22]

The motherboard may not be able to use more than 2GB, have you checked the specs? You've provided us no information to help you otherwise!