Abit KU8 User Manual page 37

BIOS Setup 3-11
32 bit Dram Memory Hole:
This item selects the method to remap the 32 bit Dram memory hole. Leave this item to its default "Auto"
Setting.
MTRR mapping mode
The item selects the MTRR mapping mode. The MTRR (Memory-Type and Range Registers) controls
the access and cacheability of memory regions in the processor.
User's Manual