Same thing happens on my Vega 20. I didn't want to go through the struggle of shipping my Mac and doing an eGPU again, especially considering the fact that this card is capable of gaming without the nonsense throttling. I honestly don't care if it's generating heat since I usually upgrade often anyway.
How does 19.2.2 work for you? It's the only version that works perfectly for me. No throttling, 1262 MHz core clock 99% usage
It doesn't throttle down to 300 MHz and back to 1262 MHz; it just slowly throttles until I lose half my frame rate.
Experiencing similar problems with big FPS drops on my 460 MacBook Pro. June Edition of the drivers hasn't fixed this either. Card throttles down hard (0-20% usage) when the temperatures reach around 70-80 degrees Celsius, but sometimes it will throttle down hard even at significantly lower temps for no clear reason. Tweaking Afterburner settings to lower clock speed helps a bit. Using an external cooling device also helps a bit.
Any way to manually tell the GPU to not throttle until much higher temps (95 degrees or so)? I'm cool with it running hot as long as my fps don't drop.
Edit: I noticed that if you change the Temp Limit in Afterburner, it doesn't stick when you save it. It reverts to 104 degrees max no matter what I change it to, but obviously the real temp limit that is imposed before throttling is much, much lower. I guess this implies that Afterburner doesn't really have control over the temp limit, and the drivers themselves do? Sry if I sound dumb, I'm kinda new at this stuff.
Edit 2: Radeon Wattman resets my 460 to its default clock settings after encountering an error, so I have to keep resetting GPU clock speeds and voltage to what I want them to be in Afterburner every time Wattman resets (crashes?). This happens at least several times a day, even at default clock settings sometimes. Using an external display seems to make this event more common.
I find that even though macsfancontrol doesn't control fan speeds on newer laptops (it works on my 2016 MBP w/ 460, a T1), if I toggle fanspeed to custom (anything) and then back to auto I'll have more consistent FPS without spikes vs if I just play in bootcamp right after switching from macOS. Doesn't solve OP's problem, but might be of use to someone.
Since last month, I have had throttling issues with the Vega 20 MacBook Pro on both Windows 10 1809 and 1903. I mostly exclusively play War Thunder, a game far less demanding than the most demanding PC titles. When it was brand new, nearly all air maps ran at 60fps at movie settings. Now after a few hours, soft throttling would occur when running on a very demanding map. Temperatures were usually 70-75 degrees Celsius when playing the game. Hitting 100 degrees only happens on instantaneous spikes. I have seen other YouTubers run far more demanding games like Battlefield 5 on the same GPU at a playable framerate at high or ultra settings. Particularly, Tally Ho Tech's 2019 MacBook Pro with 8 cores manages to not throttle even after 3 hours of gaming in Boot Camp.
Resetting SMC, NVRAM, and PRAM did not fix this issue.
At one point in 1809 it was so bad that it throttled even in games not so demanding. Soft throttling occured at one point playing Cold Waters, which people have run on much older MacBooks fine at lowered settings. Dolphin Emulator showed the same behavior in Kirby's Return to Dream Land, which can run well even on low-end computers, when Tab was held to remove framerate limit and cause turbo boost to 4GHz. It would gradually throttle to 800MHz with the fans spinning at 6000rpm. The games would get stutters due to the CPU throttle.
Windows 10 1903 was installed, and June 2019 drivers were installed. This issue is partially resolved, but it only delays the CPU throttling in War Thunder. Demanding maps would still cause lag and eventually bring down the CPU to 800MHz.
There is no way to control the fans due to access to the SMC blocked by the T2 chip in Boot Camp.
Has anyone been able to control a T2 MacBook Pro with Radeon Wattman to adjust GPU power? If so, how can this be enabled for this specific model?