Whoopsie, forgot to write what /proc/mtrr looks like :-) Here we go: reg00: base=0x00000000 ( 0MB), size= 512MB: write-back, count=1 reg01: base=0xe0000000 (3584MB), size= 32MB: write-combining, count=2 reg02: base=0xd0000000 (3328MB), size= 128MB: write-combining, count=1 Regards Sebastian