The problem is your way of testing:

PCB temp is up to the ambient conditions of a miner.
The original FW is running roughly 620-650MHz and the energy consumption is ever rising exponentially when rising the clock speed, also the temperatures are rising (more energy = higher temperatures).
Fan set and all other settings are up to some temp measurements while single board test and boot procedure.
Further mV settings are according experiences regarding optimum IC temps for best value of has hash rate and efficiency.

Nevertheless there is a much better FW available and a better cooling system.