I have individually checked each RAM chip I have and each slot on my mobo. I have 4 1GB Ram chips that work together in all combinations up to 3GB but when I use all4 it is only giving me 3.25GB. My mobo is capable of 8GB whit 4 slots ( 2GB per slot ). On boot it shows the full 4GB of RAM but in Windows XP professional OS, the system only shows the 3.25GB. If anyone can explain to me why this is and what I can do to get my full 4GB I would greatly appriciate it.