re: PC Discussion - Gaming, Performance and Enthusiasts

It supports quad-channel memory, meaning the CPU can access four modules at a time simultaneously. There's minimal performance loss using two multi-channel configurations on the same board (hence, dual channel boards have four slots), so the extra slots can be used for the additional capacity, or for the ability to use more lower-capacity modules to benefit from the better timings and lower voltage generally found in good 4GB modules vs 8GB modules.

EDIT: I typed too slow.