Ram recognized in blue slots or black slots but not both

[aowstrife]

I verified that each stick of ram and each ram slots works. 8GB will be recognized in Blue slots with nothing in black, 8 GB will be recognized in black slots when nothing in blue. When 3 or 4 slots are filled only 8GB ram is recognized. Motherboard updated to latest BIOS and running on optimized defaults.

ASUS P8P67-M PRO
16GB (4x4) Ram - Patriot G2 1600
i5 2500K
Radeon 6950
120GB Kingston UV400 SSB
1TB hard Drive
Power supply – Cooler Master GX 750W

 

[brispuss]

Start > type in msconfig and press enter key > select Boot tab > select Advanced options > make sure Maximum memory: box is unchecked; if have to uncheck box, then do so > OK > Apply > OK > reboot.

What specific operating system is being used?