Comment by nineteen999

I had a bunch of DEC Alpha's 21164 back in the late 90's I absolutely loved those machines except from the ARC/SRM firmware which was pretty horrible. We also had a Sparc64 board/CPU from Sun Microelectronics which we put in our tower case, added SCSI, video cards etc and ran Solaris. I also worked for a 3rd-party Sun clone maker around that time, we had piles of Sparc/Sparc64 boards sitting round.

UNIX probably won out due to licensing and the fact that it was available on x86-64 so much earlier - mainly Linux and BSD I guess but Solaris was there as well, VMS didn't boot on x86-64 until 2019.