ASUS' BIOS for the P5E3 Premium remains unchanged from the other Premium series boards and Maximus boards, so if you know these lot then you're straight into it. The Extreme Tweaker sub-menu contains the overclocking settings.
FSB Frequency: 200 - 800 in 1Mhz Increments
PCIE Frequency: 100 - 150 in 1MHz Increments
CPU Voltage: 1.1v to 2.4v in 0.0125v increments
CPU PLL voltage: 1.1v to 3.0v in 0.02v increments
Northbridge voltage: 1.25v to 2.05v in 0.02v increments
DRAM Voltage: 1.5v to 3.04v in 0.02v Increments
FSB Termination Voltage: 1.2v to 2.0v in 0.02v increments
Southbridge Voltage: 1.05v to 1.225v in 0.05v increments
SB 1.5 Voltage: 1.5v to 2.05v in 0.05v increments
Overclocking on the ASUS P5E3 Premium was beyond our expectations. The X38 chipset really soured our overclocking taste for this series of chipset, and with the X48 being merely a hand picked X38 chipset, we were still somewhat sceptical. However, the ASUS board managed to top out at 562MHz FSB which beats out the MSI X48 motherboard, though only by a few extra MHz.
Important Editor Note: Our maximum overclocking result is the best result we managed in our limited time of testing the motherboard. Due to time constraints we weren't able to tweak the motherboard to the absolute maximum and find the highest possible FSB, as this could take days to find properly. We do however spend at least a few hours overclocking every motherboard to try and find the highest possible overclock in that time frame. You may or may not be able to overclock higher if you spend more time tweaking, or as new BIOS updates are released. "Burn-in" time might also come into play if you believe in that.