APU Throttling on AC Power

I have a HP Pavilion 17-e049wm model laptop. Pretty nice machine tbh, except for one thing in general. When I want to play any sort of game on it, All the bios wants to do, is throttle the CPU usage down. Error being "The speed of processor 0 in group 0 is being limited by system firmware for x seconds" then usually followed by a hard reboot. The things I've done to "troubleshoot" this issue:

Bought a Higher wattage HP charger (65W to 90W)
Took apart the entire laptop, down to the motherboard
Cleared CMOS by unplugging the battery and leaving it rest for a good hour
Unseated, and then reseated the APU
Swapped out aftermarket RAM for stock RAM and vice versa
Cleaned the playdoh thermal paste that HP used and applied Arctic Silver

Now it doesn't do this on the battery. What happens on the AC charger is that under a heavy load, it limits the CPU to 2.05GHz at 83% load. But under battery power, it sits at 100% at 2.5GHz. These tests were performed using Prime95 with an extra monitor attached with temps, and speed monitors loaded)

Specs are as follows:
AMD A10-5750m @ 2.5GHz (3.5GHz Turbo)
Kingston HyperX uPnP RAM @ 1866
750GB HDD (stock HDD)

I'm not sure what else to do from here. Its upsetting me because this laptop is actually a really great laptop (can actually play Titanfall on medium settings with AAx2 and have extremely respectable fps)
PLEASE SEND HELP.