computer recommendations for 4K or 8K video?

I don't know much about codecs.  I export .265 for youtube.

I just don't want to make the kind of mistake I made with my Custom built Rain computer, supposedely able to handle all my photo, audio and video needs.  this was Windows 7 Ultimate. 8core AMD 16G RAM. I spent ~$2500 and I was getting blue screens from the beginning, and then the country went out of business or something as I could no longer get tech help.  I was mainly using for Photoshop CS6 and Cubase 8.5.  Later when I started doing video with PP CS6, it wasn't bad till I did a lot of stabilizing.  At some point the computer wouldn't boot up and a relative got it going again but recommended updates.  The processor was repasted.  I'd be in CS6 and the computer would just reboot.  I added a new video card, bigger power supply, new and doubled RAM and nothing made any difference.  I could still use with PP but then that started rebooting also. Initially I was able to run Photoshop CC but still sudden rebooting occurred.  then I had a problem where it wouldn't even run and could get no help as tech help said there is none for Win 7.  I have been doing since on my Win 10 laptop, but lots of jerkiness with videos when adding stabilization, or freezing and this wasn't even 4K yet.  I am wondering if there is a recommended brand, EG Dell with the capabilities to handle what I want to do, rather than some custom built thing whose components don't seem to work together after a total investment of over $3000.