As long as the microcode for that processor is included in the Mac Pro firmware, you should be good to go. I've installed El Capitan & High Sierra on my cMP 4,1 without issue. If it's a hackintosh, then you should be good to go.Sorry to digress : AliExpress mistakenly sent me a Core i7 960 3,2 Ghz quad core 960. Would this work in a Hackintosh with High Sierra or any other mac OS ?
As long as the microcode for that processor is included in the Mac Pro firmware, you should be good to go. I've installed El Capitan & High Sierra on my cMP 4,1 without issue. If it's a hackintosh, then you should be good to go.
Seems it’s more complicated than that. I had problems with my 4,1 after upgrading the Bootrom with 10.13.5. I could boot a finished installed macOS just fine, but I can’t do system Upgrades. Also I couldn’t boot into a recovery or a macOS installer stick. All stucked with a kernel panic.Not just i7s are C0/C1, but some early Xeons, like L5520, are 106A4 too, but seems the C0/C1 Xeons can boot macOS without microcode and C0/C1 i7s can't.
The explanation for this behaviour is simple.Seems it’s more complicated than that. I had problems with my 4,1 after upgrading the Bootrom with 10.13.5. I could boot a finished installed macOS just fine, but I can’t do system Upgrades. Also I couldn’t boot into a recovery or a macOS installer stick. All stucked with a kernel panic.
when I used a second Mac to install Mojave (or any other OS) on an external disk and then put the disk into my Mac Pro then it boots und worked fine. But nothing more.
Later I realized that there was an Intel Q1DV with C0 stepping installed (engineer sample of the W3570). I always thought it were a normal W3570. So I changed the CPU and everything’s works and I can boot everything.
It’s strange for me the Q1DV could boot a installed System, but couldn’t boot up the recovery nor a Installer or perform an update.