memory issue - usable amount of gb

[PP123]

I have an older PC, an Acer Aspire T120d, it was originally an XP machine but over the years I have upgraded the OS, graphics card, hard drive, added an additional dvd rewriter and memory modules. Am currently running Win 7 Ultimate and had 4gb ram in it, although I knew that only 3gb could be utilised. Yesterday I removed one of the sticks of ram to put in a different pc (that's another story!) now the system info states that 3gb ram is present but only 1gb recognizable, why is this? and what can I do to get it back to 3gb. I wouldn't have thought taking one stick of ram out would have caused this. The graphics card has it's own memory. Do I need to go into the BIOS?

 

[Ghostman 1]

Is your system 32 bit? more than likely..All 32 bit systems running Say Windows XP or Windows 7 will only show 3.25 gigs of ram... Even if you have 4 gigs of ram..
Yea! you need to go into your bios and check there to see if is say 3 gigs of ram, If it does not show 3 gigs of ram the try taking out the bios battery for 10 minutes, then replacing, then check... More than likely your ram is there, but Windows is just not seeing it.. 32 bit max ram is 3.25 of ram.. 64 bit will show all ram, from 4 gigs to 32 gigs.. this is determined on your Motherboard..