How to choose a motherboard for a pair of xenons?

Question

motherboards

It's just that if cheap huanan x79 then it's ddr3 4 channels. but 9 thousand rubles.
And if newer then asus for 30 thousand rubles.
And is it worth taking two 2011 xeons for games that are used. +pciv3.
Or the prospect is r3 + pci v4 ... New ...
And in general, tanks are enough for 4k games. Two Xeon .core 6 2.5 GHz.
And Juanans probably don't support crossfire?
Difficult choice. Mp budget = 10-20 thousand rubles
Collect for a year from bu xeon ... But outdated or for a couple of years to collect r3 + ddr4 + pci v4 ...? But promising for renewal.
Something I can’t believe that used. Chinese sell and without consequences xeon + ddr3.?