Actually in the second link I posted, says that updating your BIOS could be one solution to resolve this issue

Woops, somehow I completely missed the second link

Very interesting....

 

I would guess possibly bios, but it did briefly recognize, so not totally sure that is the issue. Have you tried clearing CMOS removing the button battery, I have noticed sometimes that helps even if you don't think it would. Also is it a 64 bit system running 64 bit OS? I believe the most ram a 32 bit current OS say win7 will take is 8GB.
personally, I'd test the ram too, say take out 1/2, and see if it show properly, if you want test them individually. Possible too it's something in the board, a bad slot, etc could be messing stuff up down the chain, or a bad stick. I have see cases where a stick was not properly set, but still there, cause issues on the entire ram setup. I think at least once I saw total boot failure because a stick was messed up. (I know you said you reseated, but just an example I 'd expect logical issues could act that way also.)

My best guess is bios though, as that is usually a consideration with RAM, I question though as you said it was fine at one time. anything's possible though corruption, bad firmware design, needing update, etc. First thing I'd do is a flash in this case, if it is current, then try reset. If nothing helps, the bios could have issue, even if no newer version is out, may be worth the flash. Just be sure you have it on good power source when flashing preferable if a desktop have a UPS too, if laptop verify battery has reasonable charge should AC fail. (This is very important, if power fails during flash your board may basically be toast.)

 

This is actually a pretty old thread, and the problem was solved, as mentioned in one of my last posts. The problem with it not reading the full amount of RAM was probably a combination of an outdated BIOS and a RAM stick going bad.

A BIOS update solved the read issue. I had tried clearing the CMOS several times with no success, but since it works now I don't worry about it anymore. I do appreciate the responses though

Cheers,
Matt