GPU and Memory drop when charging / plugged in

[chanlimi16]

HP OMEN Laptop 15-en0xxx
Processor AMD Ryzen 7 4800H with Radeon Graphics 2.90 GHz
Installed RAM 16.0 GB (15.4 GB usable)
System type 64-bit operating system, x64-based processor

NVIDIA GeForce GTX 1660 Ti

2 weeks ago my laptop started to become very slow, fps would drop to 10 or below when gaming. Today I just found out, when I unplugged it, everything became fast again like a brand-new laptop. I've changed the power plan setting accordingly, I tried switching the setting of plugged and on-battery, but alas still no change. 

I have checked with MSI After burner, here is the stats:

On-Battery: 

GPU : 400 MHz

Mem: 1333 MHz

Volt : ~10 mV

Temp : 48 C

Plugged:

GPU : 200 MHz

Mem: 400 MHz

Volt : ~11 mV

Temp : 44 C

Everything became significantly faster when unplugged, I have no idea why this happens.

I was considering two things to try, either fresh installing windows or getting a new charger (exactly the day the issue started happening, my brother tried using my charger on his ASUS laptop, possibly forcing it in since there is a marking on my charger plug)

If anyone else have any suggestion or idea as to why this happened, please do let me know.

Thanks in advance.

Regards,

Nat

[erico]

You should probably recheck the power settings. 

Can you take a screenshot and show us what the current settings are?

Have you considered using PC air in a can at the intake/exhaust ports to clear dust , or worse, from the notebook's cooling  system?

You may also need to consider having the thermal interface material redone. Fresh thermal interface meterial can work wonders with GPU and processor cooling.