Chosen Solution
Title says it all, here’s a screenshot from macs fan control
Where do I even begin on trying to fix this? Exhaust had always been broken, never bothered to fix as I had no idea where to begin. I just repasted both of the CPUs and all of the sudden BOOSTB stops working and BOOSTA runs at full speed all the time.
Answering this for myself, the processor was not seated correctly and therefore was causing these issues. Doh!