Dell Precision 5820 -- Looking to BCLK OC

Hi, just got this new system in for super cheap and wanted to play around with some base clock OCing with the Xeon that was in it.

Looking at the tags there are some which appear to be related to BCLK.

ICC Profile | VarStore: IccAdvancedSetupDataVar | VarOffset: 0x16 | Size: 0x1
    Min: 0x0 | Max: 0xF | Step: 0x1
                                                                                                                        Intel ICC
    Clock Frequency | VarStore: IccAdvancedSetupDataVar | VarOffset: 0x2 | Size: 0x2
    Min: 0x0 | Max: 0xFFFF | Step: 0x1
                                                                                                                        Intel ICC
    Bclk Change Permanent | VarStore: Setup | VarOffset: 0x87C | Size: 0x1
    Enabled: 0x1
    Disabled: 0x0
                                                                                                                        Intel ICC
    Bclk Change w/o Reset | VarStore: Setup | VarOffset: 0x87D | Size: 0x1
    Real Time change: 0x0
    Permanent, no warm reset: 0x1
                                          

When checking the NVRAM contents I can see that by default bclk change perm is set which made me assume that these settings were being used.

Further on in this section there was 3x copies of the “Clock Frequency” header. I changed the NVRAM values for all of these to be 102MHz (0x66) which was my initial target, however, it doesn’t seem to have any effect.

Anyone know what I’m missing? Here is a copy of the formatted setup menu.
formatted_Section_PE32_image_Setup_Setup.sct.0.0.en-US.ifr.txt.zip (39.0 KB)

While in there I did enable unsigned UEFI updates, but this is something I want to avoid for now.