SSD jumps to 100% under GPU load and freeze Windows

[NotSoFunnyClown]

I'm despair on a strange problem.

My system runs since almost 2 years without any problems. Since about a few weeks I got the problem that when I'm playing a game like overwatch, after a few minutes, textures and 3D models starting to disappear. After a while the whole game will freeze. When I try to tap out the window the other applications in the background starting to freeze and becoming unresponsive.

First thing that came to my head was the RAM. But after I opened the task manager, I saw that the main SSD (Samsung 960 Pro m.2 on DIMM.2) "active time" jumped to 100% and stays that high.

Then I have tried to reproduce this behaivor. I can easily do it when I run Furmark on both GPUs. After a few seconds, SSD jumps to 100% and applications starting to freeze. The strange thing is, it will not happen when I only use one GPU. But it's not one of both GPUs that produce this problem. I've tried GPU 1 and 2 separately without any problems. when I use both, yea... you know.

It's not a temperature problem. Both GPUs run under water. 
The SSD temperature is on a normal level.
The system is not OC

I have updated some of the motherboards drivers in the last few weeks in a month so I can't really say when the problem began. 

What I've already tried to fix this behavior:

• Installed the newest GPU driver and one of February
• Removed Norton Anti-Virus
• Check the system for malware
• Installed all current drivers from the Asus website
• Installed Samsung NVMe Driver 3.0, 3.1 and the Windows NVMe default driver
• Closed all background applications before testing
• Switched from BIOS1 running UEFI 1704 to BIOS2 running on UEFI 0802
• Reset UEFI settings on 1704 to default
• DIMM.2 over PCH instead CPU
• Disable SuperFetch
• Disable PCIe power saving in Windows
• Updated Windows 10 to 1903
• Samsung Magician says "State: Good" and "Newest firmware installed; 4B6QCXP7"
• Removed all ASUS crapware

PC-Specs

• OS: Windows 10 Pro (1903)
• CPU: Intel Core i9-7900X (delidded)
• Motherboard: Asus ROG Rampage VI Extreme (UEFI 1704)
• RAM: G.SKill TridentZ RGB 64GB
• GPU: 2x EVGA GeForce GTX 1080 Ti K|NGP|N Hydro Copper
• SSD 1: Samsung 960 Pro M.2 1TB (on DIMM.2 Socket; Firmware 4B6QCXP7)
• SSD 2: Samsung 850 PRO 2.5" 2TB
• PSU: EVGA SuperNOVA 1600 T2
• SLI-Bridge: ZOTAC SLI HB Bridge / 2 Slot

Any ideas, what the problem could be? The last thing I can try is to reinstall Windows but I'm not sure if this could fix that problem. The whole behavior makes no sense for me.

I'm gonna cry :( My baby is so sick :'( :D

Thank you 

[nick name]

It didn't happen to start when you got Windows 1903 did it?

[NotSoFunnyClown]

No. It was there before i've upgraded to 1903.