First thing that grabbed me was PowerPlay size is so close to Tonga / Fiji / Polaris, but Rev 08:01 vs Rev 07:01 in the prior mentioned GPUs.
VEGA PowerPlay has OD limits as:-
80 A9 03 00 (2400MHz) ULONG ulMaxODEngineClock; /* For Overdrive. */
F0 49 02 00 (1500MHz) ULONG ulMaxODMemoryClock; /* For Overdrive. */
ODMemoryClock on Fiji was 500MHz, ie it's stock speed, perhaps there will be headroom in this aspect :thinking: . What scaling!? it wasn't much on Fiji going from say 500MHz to 545MHz in case situations I tested.
32 00 (50%) USHORT usPowerControlLimit;
By the OD limits we have 50% PL limit.
MclkDependencyTable, min 167MHz HBM max 945MHz, 4 states. Fiji had only 1 HBM state (500MHz), it was possible to modify PowerPlay to have more (video/post in Fiji bios mod).
GfxclkDependencyTable, min 852MHz max 1600MHz, 8 states.
7A 00 (0x7Ah) USHORT usVddcLookupTableOffset; /* points to ATOM_Vega10_Voltage_Lookup_Table */
8C 00 (0x8Ch) USHORT usVddmemLookupTableOffset; /* points to ATOM_Vega10_Voltage_Lookup_Table*/
Viewing VddcLookupTable, lowest state as 800mV, which is 100mV lower than stock Fiji. Highest state is 1200mV. How this lookup table is used for when ASIC profiling is done no idea at present, Fiji max 1250mV.
VddmemLookupTable has 1350mV, no idea if this is HBM voltage or something else. Fiji did not have HBM voltage in PowerPlay, nor was it 1.2V, but 1.3V. Not read about HBM2 at all TBH, but would have expected it lower or 1.3V, perhaps AMD needed to give it a bump if this values is indeed that.
Ref'ing the Linux info, there are 2 slightly differing setups of PowerTune, one I believe is for the AIO version and the other for AIR version. PowerTune_Table_V2 I believe is for the AIR version.
5F 00 (95°C) USHORT usTemperatureLimitHBM;
HBM2 has a temperature limit in PowerPlay, Fiji did not.
AFAIK HBM1 should also have had a temperature sensor, as JEDEC PDF highlighted with increased temps HBM should lower performance to reduce temps. No monitoring on Fiji showed this temp, either it was not implemented or not exposed for SW to show.