How do differences in supporting-hardware/density change the effective pricing? It seems to me like the Phi cores could end up cheaper once you factor in everything else that you need to get that many cores of something else.
The 50-core Xeon sounded great up until the $2600 price tag. You can buy a lot of CPU cores for that much money if you have quad-socket boards like that.
That's $44.15 per 1 GHz core.
AMD FX-6300 Six-Core 3.5GHz is $138 = $23 per core (and much faster cores).
Intel Xeon 5148 2.33ghz is $18.