HP 255 G8 Laptop throttles when charger is plugged in.

[MaxLiner]

Hello, I have an HP 255 G8 laptop that I bought last November in 2023. The laptop has a Ryzen 5 5500U. About this laptop, since the beginning of my purchase, it has a problem. If I insert the charger, the laptop runs slowly, the temps are normal (not going above 70 degrees on factory thermal paste). If I look at the task manager, the frequency of the CPU immediately drops to 0.4Ghz, repeating continuously when I plug in the charger. After I checked in HWINFO, it turns out that there is 1 parameter called PROCHOT EXT that is marked yes. But I thought it was a problem in the BIOS. But if i use battery power, it's normal, the frequency back up to 3.4-4Ghz constant range and there is no problem.

After several months of waiting for BIOS updates from version F.37 to F.40 but there was no change even for this problem.

Just yesterday I added RAM to 16GB from Micron, changing my CPU thermal paste to Honeywell PTM7950 (temps do not climbing higher than 65 degrees), and also added thermal pads for the VRM, also for the VRM controller (I generally think this is the root cause of PROCHOT EXT marked yes). But still, if I plug the charger into the laptop, the laptop still throttles to 0.4Ghz.

Till today, i have no clues what causing it. ive tried using different battery, replaced the original charger, and also try to charge it in different electricity grid (with good grounding).

Can HP atleast fix this issue from the BIOS or anything? my experience using this laptop are terrible since the BIOS is also limited. and also very annoyed when playing relatively light games such as Minecraft that stutters badly when it is being charged.