@dexter @lw depends how one defines "desktop systems".
I have a Talos II dual socket which hangs out around head height a few feet from my desk in one of the racks, which idles quieter than most gaming boxes. I only bring that up for comparison purposes because 144 cores of power9 doesn't limit its use to the datacenter โ it requires a good understanding of airflow requirements and case design.
So, on that I will stand behind the statement that at least the scale-out series of IBM LC922 2U servers could be repurposed into a quiet enough 4U chassis with multiple 120-140mm 1.6-2K RPM PWM fans โ ideally a supermicro case since IBM already contracted them to make the LC922, so the SMBus and PMbus connections would not need conversion โ substantially simplifying the effort for desk use.
There are occasions when one finds them on eBay, sometimes even a few. Otherwise, I've only seen Raptor.