Gave up on using a Ryzen 9 5950X with a B450 MSI Tomahawk motherboard - too unstable

 So after much time and effort trying to stabilize the Ryzen 9 5950X with the B450 Tomahawk, I gave up and just got a B550 Tomahawk motherboard. All the things that should have worked on the B450 motherboard now work on the B550 motherboard. Specifically, you can run it at default "auto" BPO settings. You can run it with PBO enabled. You can run the ram at the XMP-1 and XMP-2 profiles (3200Mhz). I can even max out the system's cooling at hit 90C on the processor. Nice.

So what went wrong with the B450? No idea. It's probably power/VRM related but it could also easily be electrical interference related as well. All I know is it it kept giving me the same error: black screen and it needed to be reset at the power supply switch because holding down the power on button didn't work.

Fun facts, if you run the 5950X with PBO explicitly disabled AND you set the ram to 2133Mhz, it runs reasonably stable but will sometimes crash after a sleep. Increasing the RAM bus speed or turning on PBO will make it more likely to crash. Weirdly setting the PBO power limits to the motherboard limits didn't seem to hurt stability that much. In fact there's a chance the stability was a little better. It makes intuitive sense at first glance but AFAIK the motherboard power limits are higher than if you simply disable PBO.. and setting higher limits should cause more instability.. so I'm a bit suspicious of my subjective stability experience.

Another interesting factoid involves the RAM compatibility list that MSI produces for that motherboard. Initially they didn't differentiate between the 5000 series and the rest but since then they've revised it so that the 5000 series had a different list with no ram listed as being compatible over 2666Mhz. Recently I can't even get MSI's website to produce a ram compatibility list for the 5000 series processors. I'm guessing this means MSI has noticed the board is flaky with 5000 series processors.

I'm putting this out there to save people a bit of time if they're having trouble with 5000 series Ryzen processors on the B450 Tomahawk board. You're not going to find stability nirvana with that board.