Yeah, it's called Transaction Booster, but sadly in the P5E3 BIOS, we do not have the "manual option" so we cannot set a common performance level, it's some strange guess work.
Transaction Booster = Enabled Level 2 usually gives you a performance level of 7, enable level 1 = PL8
Disable Level 1 = a slack 8, Disable Level 2 = PL9
I wish ASUS brought our BIOS in line with other P5E3 X38/X48 boards as they have a Common Performance Level option under Transaction Booster
John