Question Why all my games are stuttering and I got low 0.1% and 1% FPS?

[Heartnett]

Hello all, I have been gaming on my pre-built PC with a second hand MSI GTX 1660 Ti Ventus XS for over a year with no issue. Then I decided to change the thermal pads and paste of my GPU because I noticed a spike in temps.
Ever since I changed the pads and paste, I noticed unexplainable stutters suddenly emerging from every game, regardless if I play on high, medium, low or even on 720p resolution. I got a pretty standard office desk HP EliteDisplay E231 60Hz monitor; but I didn't see these stutters when I bought my PC. My CPU and GPU temperatures never pass 70c on max load. I game on HDD but I moved Arkham Knight and GTAV to my OS SSD but with no improvement. Also I always cap my FPS by RTSS to 60FPS. And for the record, I always monitor my hardware, I never noticed a sudden drop in wattage/usage/volt/clock on any of the GPU, CPU and RAM WHEN the stutters take place.

Here are pictures of Arkham Knight and GTAV captured with CapFrameX:
The Arkham Knight Comparing down below was before I turned on high priority for the .exe file on task manager.

My rig is following:
GPU: MSI GTX 1660 Ti Ventus XS
CPU: Ryzen 5 4500
HDD: 1TB Baracuda
SSD: 250 Zicron Sata
RAM: Kingston Fury (2x8Gb) 3200Mhz
MB: MSI B450m Pro VDH-MAX
PSU: Micronics Classic II 700w 80+ Silver

Things I have tried:
-Enabling and disabling XMP profile
-Undervolting my CPU and GPU
-Using DDU to uninstall GPU driver
-Disabling fTPM
-Disabling Windows Defender
-Disabling HPET
-Updating MB BIOS, GPU driver, CPU Chipset to the latest update
-Removing keyboard and mouse and playing with gamepad
-Removing case frontal USB off the MB (cause I read online it could help)
-Repasting GPU and CPU
-Setting the games priorities to High on task manager
-Turning on Ultimate Performance from power management
-Reinstalling Windows 10 and debloating it with Christ Titus Tool

I'm absolutely losing my mind, I thought of swapping GPU and CPU with local shops but it isn't possible. And could really use your help guys.

 

[rgd1101]

brand and model of the 600w psu?
how full are the ssd?
cpu/gpu temp and usage during the game?

 

[JohnBonhamsGhost]

Ever since I changed the pads and paste, I noticed unexplainable stutters suddenly emerging from every game...but I didn't see these stutters when I bought my PC

likely you damaged the GPU.

PSU: 600w

include the make & model

 

[Heartnett]

brand and model of the 600w psu?
how full are the ssd?
cpu/gpu temp and usage during the game?

Micronics Classic II 700w
My SSD is 50% full
CPU usage when playing GTAV 20-30% reaching 39-44c
GPU usage 40-60% reaching 40-50c

 

[Heartnett]

likely you damaged the GPU.


include the make & model

I’m 100% certain that I didn’t harm the GPU
the PSU is Micronics Classic II 700w 80+ Silver

 

[JohnBonhamsGhost]

100% certain that I didn’t harm the GPU

so you think it's just a coincidence that this started directly after you manipulated the innards of the card?

Micronics Classic II

this is a pretty low end unit.
even if it isn't a contributor to the issue(s) you're facing, i would replace it asap.