Originally Posted by TwoCables
Oh. Then what they're referring to is having all the slots filled as opposed to exactly half of the slots (6 sticks vs. 3 sticks). Having all of the memory slots filled puts a little bit more stress on the northbridge which has a history of making it slightly harder to overclock.
However, another limiting factor can be the power supply because it is extremely important to be getting clean and stable power from it.
In addition, it's the settings. Unfortunately, I don't know how to overclock a 1366 board yet so someone else will need to help with that. Fortunately, there are several experts on here.
So, it's not because you had 12 GB, but it was because all 6 slots were filled.
This is not always true. As my P5Q-E overclocks 2x2GB + 2x1GB (Single sided) (All slots filled) just as well as 2x2GB. However, 4x2GB overclocks much worse.
So it's also about the size of the sticks and if their double sided or single sided. I've also found that even with all sticks dual sided, in a 2x2GB + 2x1GB configuration, still overclocks alot better than 4x2GB.