Hi
If you see the UEFI Firmware Writer's Guide https://communities.intel.com/docs/DOC-22477 you’ll see that if you want to increase the speed you’ll need to follow the physical address range, this is located in table 12 page 24 “eSRAM, Memory Msg Port 5:R82h 512 KB, (Address=80000000h)” If you would like to change this range for another this must be done in the BIOS first.
Regards
JPMontero_Intel