Hi fellow members and Asrock support person !

I own a Fatal1ty X99M Killer/3.1 board and i'm happy with it however, it seems the NorthBridge frequency is locked to 4300 no matter if i increase the cache frequency above this speed ( 4400 or 4500 ). I can input this speed into the bios and it saves no problems but when i use AIDA64 or CPUID (latest versions ) it's showing the northbridge frequency is always at 4300. This is with a 5820k and GSKILL 3200 DDR4 Ram.

My over-clock is 100% stable etc.I'm running the latest bios version 1.3. Iv'e tried it with the previous version and the results are the same.

My question is - are these boards locked at 4300 or are the programs i'm using wrong ?

Thank you for your time !