Like the previous post says, make sure all the stick work first of all.
A BIOS update "may" sort it, best to have a look on your mobo manufacturers website. What is then maximum ammount of ram your mobo can take?
Well you aren't really helping by asking ME how much it can take. I've read it can take up to 4Gb, but I'm asking for advise just in case.
The reason I'm asking for help is because it's stated that it can take up to 4Gb (altho theres some notes on slot "population" i don't quite understand). Had I read it can only take up 3Gb I wouldn't even have bothered to make a new thread.
After a quick google search - google is yur friend!
I found some mention of that motherboard having issues with running 4 sticks of double sided memory, could this be your case as well?