I just installed RAM and my computer recognises but doesn't use it

[Zyzyoro]

I originally had 1 GB of RAM. The motherboard is compatable with only DDR RAM. I have two 512MB DIMM DDR SDRAM sticks originally, and I just installed a 1024MB DIMM DDR DSRAM stick. I right-clicked "My Computer" and it still says 1GB not 2GB. why? Hopw do I configure my system so it can use and read my new stick of RAM?

 

[TheGr8schlotzky]

i've heard of similiar problems, but the only thing they found to work was reformatting.. :-\
you may also play around with the bios to see what you can find..

 

[Zyzyoro]

no, i DO NOT want to reformat. any other ways? i need a lot of help with this.