[benbenolson]

That's almost exactly what the Xeon Phi was, both in coprocessor form and in machine form. It included MCDRAM, too, which was a high-bandwidth memory. Very efficient, but lacked sales; people didn't want it.

Part of that, I think, was lack of parallelism in applications: in order to fully take advantage of those cores, you need to have a nearly-embarrassingly-parallel problem. Otherwise, you're not going to get the performance that you'd expect (but you'll get power efficiency!).

The fact of the matter is, that's not "all anybody wants."

[adgjlsfhk1]

also, of you're problem is embarrassingly parallel, you can probably run it on a GPU and it's will be faster.