AMD AM3 DDR3 support is really up to 1333. Your only really suppost to run two sticks, one in each channel if you have DDR3 1333 or above. I have ran 4 sticks with no problem. You just have to go into the bios and manually set the memory speed, voltage and timing. With 4 sticks you might have to bump up the CPU N/B voltage. OC means Overclocked.