Dead as in no longer produced? Yes.
Dead as in not able to run a current OS? Probably.
I can remember these beasties, although I would not have known anything about them without a
search.
The later ones could run M$ NT on multi-P5 CPUs, but if you have a CP/M floppy laying around the ICLs worked great with that on 128KB RAM!
But use only near a hydro-electric source to avoid causing brownouts...