It's quite impressive what they were able to achieve with ppc64el in recent years, including Linux support for it, too. Unfortunately, they turned the wrong way with proprietary encryption of memory, which may or may not be deliberate as far as backdoors come and go, but in all honesty so much in it is contingent on IBM's proprietary fabric (OSC or what was it?) implementation for tiered memory anyway. There's similar setups from Samsung, even including fully transparent swapping to NVMe for persistence which is really cool, and hard to match in open source setting.

I think their slogan could be "unlimited, coherent, persistent, encrypted high-bandwidth memory is here, and we are the only ones that really have it."

Disclaimer: proud owner of thoroughbred OpenPOWER system from Raptor