How about a Mac Pro Hackintosh ;-}
Basically, strip out the logic board and put in a ATX board in with a better CPU. I would even toy with going with an i9 chip!
You’ll need to do some reading before you go down this path [https://www.tonymacx86.com|TonyMacX86] is a good start and here’s a person who did it [https://www.insanelymac.com/forum/topic/277025-how-to-the-perfect-hack-pro-mac-pro-build-using-an-original-mac-pro-case-parts/|The Perfect Hack Pro (Mac Pro) build using an original Mac Pro case & parts]
Here’s a supplier of the needed conversion parts [https://www.thelaserhive.com/product-category/mac-pro-kits/|Mac Pro Conversion Kits]