Doesn't exist. I doubt you could even find one that has a terrabyte of RAM.
The thing is, it's kinda pointless to have that much data stored in a temporary memory that would all be erased if the power shut off. If you're going to be processing that much data you might as well use a permanent form of storage.
I mean, you could probably get it to work in a server with SSD's. They can load data faster than processors can handle in some cases.
Otherwise, you'd probably have to build the system yourself to have 1 PB of RAM.
Server units in a "farm" that might possibly have enough slots for 16GB each strips or even larger special ones.
Here is 1 PB of hard disk space from a decade ago: https://www.engadget.com/2006/01/30/emc-…
Here is a newer version: https://www.backblaze.com/blog/petabytes… where 1 PB would be less than $16K
Cost? What Bill Gates cleans out of his sofa cushions–a few million at least.
a workstation. oh its gonna cost a lot. Workstations are fit in with "quantities" of powerful parts, mostly best of the best.