OS-WINDOWS 7 ULTIMATE 64BIT
MOBO- ASUS P7P55-M
OPTICAL- ASUS DVD/CD
HDD-160GB SATA WD, 180GB EXTERNAL USB
IM FAIRLY NEW TO BUILDING PC'S AND THIS IS MY FIRST,HAVE A BIT OF EXPERIENCE WITH BIOS, ANY IDEA HOW TO FIX THIS AND TAKE ADVANTAGE OF MY RAM? IT ALSO SEEMS TO RUN AT 1333MHZ IN THE BIOS? HAVEN'T DONE ANY CPU OVERCLOCKING NOR RAM, JUST GPU. IF YOU COULD EXPLAIN HOW TO GET MY RAM TO 8GBS AND 1600MHZ THAT WOULD BE GREAT! SORRY ABOUT ALL CAPS, BROKEN KEYBOARD...
If you have a 64 bit OS it should show you have 8gb RAM even without going into the bios to manually set everything. You could try try one Ram slot at a time and see if one slot is not reading the RAM/ the RAM is not fully inserted into the slot correctly.
About the speed issue, the above poster is right about goin in to the bios and manually setting the memory speed to spec.