If OCCT is causing your PC to blackscreen on any test then there is something seriously wrong.
Check the version of DirectX that is installed in your Windows OS and make sure it is up to date.
I think you ran all Windows Checks and they passed.
However ... sometime Windows install just gets corrupted and even though those Windows Checks report o.k. they might not catch everything that can go wrong.
I think it is a good idea to try a fresh install of latest Windows on a new SSD or SSHD and then install the latestAdrenalin drivers for the card and see if that works.
I have DirectX 12
I installed the windows around 6 months ago, usually every year i do a format and a fresh install.
But i will try a fresh install in a bit.
Sounds like that is the best thing to do, or at least RMA the AMD card.
First fit your old Nvidia GPU and run OCCT tests to make sure your PSU and RAM are o.k.
Sorry I cannot be of more help.
I did that and all fine, so its a driver issue or GPU issue for sure. its just insane after almost 6 months of the GPU being out for sale and having this type of issues.
You should have seen the RX5700XT fiasco. It took ~ about 8 months before they fixed blackscreening on that GPU, and even longer to sort out other bugs & stability.
On the plus side, RX Vega 64 Liquid (AMD highest end consumer GPU at the time) - it was years before that got fixed.
The RX Vega 64 Liquid works well now.
It is actually my favorite AMD GPU so far, especially in the winter... 360Watts GPU power.
I know thats why i went with Nvdia with those cards. I always liked AMD even when they were the underdog my last AMD GPU was a R290X and it was good. I didnt saw so much issues with this Card until i got it. Then posts start to appear everywere with the same issue.