Question What is the best kind of E5 v4/v5 Xeon processor

[ComputerFingeringMan]

Right now they are cheap ones flooding form China in Malaysia. So I was eyeballing cheap pc components to see what franken parts I could shove into some old dusty late 90s case or my cooler case. I have been seeing that X99 pieces and Xeon processors are pretty dirt cheap. I don't get which too pick as there too many types. The Soyo mobos which I read are just rebranded Maxsun boards. Which I heard are the best in terms of reputation and quality.

I am presuming that a higher GHZ is better as it can match a I7 K models. Plus can it be paired with some old 10 series/16 series maybe the 20 series?