hi guys, see what your thoughts are on my current problem which seems to be getting worse.
Recently well starting this year getting d3d failures. Which the gpu would recover. Now am getting in random games. Massive frame drops for around 1 to 2 minutes then it would recover. (200fps on average dropping down to 15fps) its like the gpu stops and the cpu takes over). Last night i had to reboot for it to recover.
My specs
2080ti xc ultra (preorder)
9900k at 5ghz
32gig hyperx
Corsair 850i psu (brought at the same time)
My gut feeling is the gpu is starting to fail. (Strange d3d failures and now massive fps drops, some random reboots which cause the fans to ramp up to max)

I have checked temps when i started having problems, running the gpu various stress tests. Some throttling but nothing to cause the gpu to crash or reduce the frame rates by 90%. Running warthunder @4k dropped frames by 90% but recovered but had a few d3d failures. Last night on worldoftanks @4k normally pushing 200fps. All of sudden dropping 15fps it didnt recover , that was 2 games straight. What ever is happing its getting worse

Lock your FPS to your screen's refresh rate and see if that improves anything.  I expect if it goes way too high that the CPU bottleneck might come in play even though your CPU is perfect for gaming.

weird thing is ,i have had the card from day 1 release, no problems, its not worth overclocking it as its so fast, but the past couple of months weird errors and now suffering with a collapse of fps.

Win10, with the updates. Still on the previous nvidia driver. I dont install geforce experiance, and since the start of the problems i dont have afterburner installed anymore.

The 1st signs i did suspect the psu (i cant rule out) and i have doubled checked the cables and single rail settings. I have monitored the 12v and it looks stable when i have stressed the system. Corsair hx850i psu

I think better is to check what is actually going on with something like msi afterburner. You need to check what changes when issue occurs: it could be something related to hardware like gpu or cpu clocks down or gpu voltage drops or something like that. Or it could be some software issues like for no reasons gpu usage dropped to zero.

Easiest way to find out:
 
Test the suspect GPU in a different PC (that can handle it).
 
Or,
 
Test a new GPU (preferable close in wattage load) in your current PC to see if the same thing happens with it.
 
Or,
 
Bring your PC to a PC repair shop and have them test the above.
 
 
Coming in here late, if you haven't removed all overclocks and tested that would be a good start. I've had random reboots for my PC from unstable overclocks (some motherboard voltages on auto were not completely stable. Is your motherboard BIOS updated? Strange issues have been resolved for others by doing so (just make sure to set BIOS defaults before you flash a new update). Have to tried a fresh windows install? I've had random BSOD/reboots solved with a fresh windows install since windows 10 in-place feature updates sometimes have serious problems when not fresh installed (be sure to back up any files that you want to save first). Also, did you make sure all of your power cables are securely plugged in? All of the motherboard cables and GPU cables, and if it's a modular PSU, on the PSU side as well?