I just re-looked at them and the main differencebetween them is that the extreme supports 4 way sli/cf and the formula is 2 way, which is all I plan to use and the formula has a really good integrated sound card, which was a big selling point to me where the extreme has a standard I believe. The formula also has some thermal metal/back support being a heat spreader on the back and a nice covering in the front. Also, if you plan to use liquid cooling, the formula has an integrated loop for the chipset I think.