Gigabyte uses System memory multiplier. It is also known as ASync Memory ratio on some boards. It actually serves the same purpose, allowing you to run your DDR2 modules in ASync to your CPU CLK. For example, X6800 is running on 266MHz, and if we set the ram to run at 533MHz, that is running in Sync, in this case, the multiplier will be 2x.

PCIe Overvoltage, set up to +0.3v

FSB overvoltage can be upped to +0.3v

CAS Latency, RAS# to CAS#, RAS# Precharge, tRAS ar some of the common DRAM timing adjustments that needs no furthur introduction. Set it accordingly or set to AUTO to use SPD values.