The official BIOS locks memory tweaks to basic XMP profiles. The exclusive BIOS unlocks full , command rate, and even VCCIO/VCCSA voltages. This is critical for running cheap server DDR4 (2133MHz) at tighter timings or overclocking generic 2400MHz RAM to 2933MHz.
While some newer "Pro Max" revisions include this natively, older "Pro" BIOS versions often have these modules hidden via obfuscation; modded BIOS can reveal them for Windows 11 compatibility. Key Motherboard Hardware Features [Request] Machinist X99 E5-MR9A PRO V1.1 BIOS Dump machinist x99 mr9a pro bios exclusive