Make sure that you look into this RAM problem with the MHz issue. It's never good to cross match RAM MH'z freq that is below or above the requirements for your mobo and/or if you're putting in different sticks of RAM.
Also, I would not recommend you overclocking your CPU on a stock heatsink, maybe upgrade heatsink? You can overclock your CPU on a stock heatsink, but just don't go crazy with it. You'd be at high risk of frying things.
Take notice that any warranty on your CPU would be voided if you remove the stock heatsink and put in a better/upgraded one unless it's a special bought warranty that says you can. Most warranties don't cover that.
