none.... i have the P5E and its amazing..... i can run my quad at 4gig for benching and 3.6-3.8 24/7. the bios for both boards are now almost identical. the initial bios the board comes with doesnt have as many options as the maximus bios but the update has virtually the same settings as the maximus.... its £70 cheaper than the maximus and if you look under the P5E sticker on the board youll find it is a maximus. its just the lcd poster crap that you dont get and a reset button....