Weird Thermal Throttling Problem

[basilv12]

Hello everyone,
I recently bought a ROG G703VI and I'm having some trouble with performance deficiency issues.
While on idle, 7820HK CPU seems to be working at about 50 degrees celcius but the strange thing is it jumps to 80 degrees for just a second and then falls down to its normal state as nothing happened. My initial guess was that it was just caused by a glitch, but gaming and some monitoring shows otherwise. While gaming, from time to time I notice a fps loss which lasts about 1 or 2 seconds. I checked the CPU usage and temps with XTU and thermal throttling was spiking like crazy. I tried undervolting about 0.005-0.01V but the problem still persists. I maxed out the fan speed to observe how CPU temp will react. Apart from a few degree decrease, it still hits 97-98 celcius randomly. I've attached the weird screenshots I took from XTU while gaming. Could it be because of a faulty BIOS? Or is it a hardware problem?

 

[basilv12]

https://imgur.com/6Tpe300
https://imgur.com/djBeJ8Z
https://imgur.com/wshxsxc
These are the XTU graphs I monitored while gaming

 

[effable]

All possible fixes.

- Open laptop and clean the dust.
- Redo thermal pasting with a really hq one like the arctic's and the thermal grizzlys.
- Buy a opolar lc06 (laptop cooler which connects to the vent, cools it down and extracts heat from the back, this one is specifically for your laptop as yours has the heat ventilation on the back so you can easyily attach it. it's known to reduce temps by 10-25 degrees

 

[basilv12]

I thought of dust too, but wouldn't it also affect the GPU temps? They seem to be fine for now. I'm also thinking of insufficient or ineffective thermal paste. Would it create temp spikes this huge?