If you don't care about electricity and you want to mine only YTN, then Xeon W3565 should give you similar results like mine one (500 h/s or more).
Search (or ask somewhere) how many hashes you'll get on Core i5 4570 (IMO something about 450 - 500 h/s, but that's only my estimations, I didn't check it by myself).
What software are you using, I get a measly 40h/s for each of the 8 CPU's in my parents i7
cpuminer-opt-3.7.8-windows-v2 (cpuminer-sse42.exe).
I'm getting 500 - 520 h/s on all eight threads (more than 60 h/s per thread).
Config:
CPU: Xeon X3440 @ 3,2 GHz (4C/8T)
RAM: 2x4 GB @ 1680 MHz 9-9-9-27 1T