Is it showing 96C when idle or during tests?
On your screenshot in the first post there was no VR MOS sensor information
Technically it's the mainboard (chipset) temperature, it's not related to the VRM and it doesn't seem to be working properly.
Try to run the games you had issues with earlier (Enlisted and Wreckfest) to check if there will be throttling
Could be a bios version or some thing like that!! By the way a have this problem but the temperature is normal never get 60°C on CPU also on motherboard
(my board is msi a320m-a pro max)
Still searching for solution...
If you have 3400G running on a320m-a pro max then most likely the issue is the same.
There are no SoC VRM thermal sensors (which you can observe with software) on most budget motherboards, yet these motherboards aren't capable of providing Vega11 IGPU with enough power under full load during long gaming sessions due to SoC VRM throttling.
It's a hardware, not a BIOS problem.
The solution would be the same with OP's here and in this thread https://community.amd.com/t5/graphics/please-help-ryzen-5-3350g-drop-in-frequency-of-igpu/m-p/466854...
Well i guess it's a problem with cheap motherboard then and it's vrm isn't good enough to deliver enough power to the APU. I'm going to mark this as a solution (Buy a better motherboard with more power delivery phases and a good vrm cooling) and end this topic. Thanks to everyone who took their time to reply and try to help.