I was using 2GB DDR2 RAM. 2 weeks ago i got bought another 1GB ram and put that in the RAM slot but my computer only shows 2GB instead of 3GB. I tried clear CMOS. its still showing the same thing.

ABIT KN9S MOTHERBOARD

Did anyone had the same problem?

does it show you have 3 in your BIOS? I had 2gigs, then put in another 1, and Windows XP Pro (32) only shows that I have 2. Yet, my BIOS says I have 3, and CPUZ says I have 3 too. What OS do you have?

bios says 2 aswell.

iam using vista ultimate 64bit

is it just a single stick of ram or is it 2x512?
try the 1gb on its own (without the 2 you already have) to make sure the ram isnt faulty

Its 3x1GB. yeh i will try that later and let you know. thanks

Most motherboards run dual channel (your board does). You will need 2 or 4 modules for the motherboard to work properly.

Even if it let you run 3 you would be in single channel mode which is worse for performance than only running with your original 2x1GB installed.

Your motherboard is trying to tell you to something, listen to it. Or read the manual which would have answered your question already....

Someone mentioned last night that many mobos these days can run both dual and single channel simultaneously... now I don't know what to believe

Some can.