1GB of Ram showing as 512MB

Yep, im stumped. Ok, so my PC currently has 1GB of Ram, however most of the time it only shows as 512MB in the system information. Occasionally i get lucky and it shows it's whole 1GB but im just wondering why it's only comming up with 512MB when it chooses to do so.

I have the exact same PC model as my mother's although she isn't experiencing any problems.

The model im using is:
http://vaio.sony.co.uk/view/ShowPro..._cons&pageType=Overview&category=VD+XL+Series

Any ideas? Note im pretty computer illiterate when it comes to these things. Though my mother's a bit more educated in this department.

Any help would be greatly appreciated.
Thank you.

 

Have you got all your updates...Windows updates and have you gone to the Sony site and see if there are any updates for that model ie Bios updates etc.

 

Also you could have a loose memory stick.......if you know where they are usually under a trap door on the underneath with 4 phillips screw

 

Do u have any video card installed or using 2x512 chips

 

I'm not an expert at all, but just wanted to say that I experienced the SAME thing (my comp sometimes recognizing it but not always) for about two days and it turned out that the chip was not inserted all the way in. I had added RAM chips before and thought I'd pushed it in more than enough but I guess how hard you gotta push is different from one chip to another.