High End PC,games run fine for ~20 minutes, then it starts stuttering/input lagging and screen tearing,Framerate Stable

My current Rig that i upgraded a few days ago:
-Gtx970 G1
-8GB DDR4 2664MHz Vengeance
-i5 6600k 3.5GHz OC'ed to 4.0GHz with hyper 212 evo cooler
-z170x gaming 3 Gigabyte Motherboard
-win 7 x64
-1 SSD EVO 840 250GB (Windows 7,Google Chrome, Rainbow Six Siege and GTA V installed on this disk)
-1 Seagate HHDD 1tb(8gb ssd) 7200 rpm (2 years old, for apps and other games)
-1 Seagate HDD 1.5tb 7200 rpm (for files and media)
-720 WATT 80% efficiency PSU.
-Mionix Castor Mouse.
-Zalman Z11 mid-to full tower case.

I used to have the same issue with my previous rig before i upgraded my RAM,Mobo,CPU, which used to be:
-i5 760 2.8ghz OC'ed to 3.5GHz stock cooler and later added the hyper 212 evo cpu cooler
-8GB DDR3 1664MHz RAM
- a cheap Asus Mobo that used to cost 50-60 euro 6 years ago with PCIE 2.0 that supported my GTX970.


My issue:

I am playing(even with my older build) games like Rainbow Six Siege on max settings 1080p 70-120 fps, after a while(10-20 min) there are a few freezes and fps drops, then after the freezes there is a noticable input lag and screen tearing and choppyness and lack of fluidity overall that ruins gaming completely.


I've got no clue what's causing it, this is a new PC practically that i paid 500 euro to upgrade a few days ago for the MOBO,RAM,CPU , i formatted it, installed latest drivers. When i am running the game, i alt tab, my CPU is at 40-70% workload and my ram at 70-80%. I got no background programms/anti-virus running or anything.
My temps are completely fine(32-44 CPU,28-35 MOBO,44 GPU,) wether i overcloack or not, it doesn't affect that issue.

In games like R6S the input lag/ choppyness will come into play after 15-20 min after the first freeze during preparation phase. In games like GTA V, Rise of the Tomb Raider, it will start input lagging and screen tearing after around that time or whenever i save or load a new area on RISE OF THE TOMB RAIDER(it's on my HHDD)

While the game is input lagging/choppy/screan tearing, my FPS are fine above 70 smoothly and unaffected. No matter my Graphic Settings/Resolution etc. it doesn't stop it from happening. After ~20 min the game will start having an unplayable input lag and will get progressively worse.

My older Rig, my CPU used to run on 80-90 temps with it's stock cooler oced at 3.4ghz, then i got the h212 evo and it used to run at 60-70 on 3.5ghz and i thought it was causing me the issues in combination with my broken motherboard pins on the CPU socket, that had disabled my 3/4 RAM Slots and i only had 1 8gb DDR3 ram running. I thought that was causing the instability, but it isn't

I don't know what to do.

I recently saw that my 1.5tb HDD used to run on 50 temps, but i changed it's location and added a fan on the HDD area, so now my HDDs are at 35 and 42 temps and my SSD at 42.

I've researched this and i cannot find anything that can help me.I also saw people saying those are usually Graphics Cards not connecting properly with the PCIE slot or faulty PSUs, but i never had issues like that and i used to run R6S back in December when it came out, just fine with my previous rig and now even better with my current rig,yet no matter what game i seem to play, after ~20 min input lag and screen tearing will start showing.

Even when playing GTA V with a controller and VSYNC and Motion Blur, when i move the camera, it will teleport to some angles, due to chopiness/screan tearing.


Too Long Didn't Read:

-Temps Fine
-Newly Formated PC and all latest drivers and MOBO updated BIOS etc.
-FPS indicate just fine
-CPU/RAM Workload is just Fine
-Disabling/Uninstalling Geforce Experience/ Canceling the Overcloack etc. doesn't affect anything.

So anyone can tell me what the hell is going on with my RIG? Obviously my MOBO/CPU/RAM were not the reason it was causing those issues. Could it be my PSU? ( doubtfull since it runs games fine for the first ~20 min) Could it be my GPU? ( don't know how it would be that, since it alaso runs games fine for the first ~20 min)

Restarting the PC doesn't fix anything, not playing for about 30 min will bring me back the 100% performance/no input lag/ no screen tearing gameplay for another 20 min.

P.S. It also has nothing to do with electricity wiring as i also happen to change house this last week.

I have seen similar issues with similar older computers, it just seems that the older components start to drop in performance over time, especially power supplies that weren't built to last. I would have suggested that you might have memory leakage, but that sounds unlikely seeing that you said RAM usage was fine. I'd swap another power supply in, and if that doesn't solve anything, try swapping the RAM. It is possible to have GPU RAM leakage, but that is a very rare situation.