I had exactly the same problem with the same model of motherboard.

check the cpu socket for bent pins - use a magnifying glass if possible.

the easiest way to check is to look the underside of the cpu, there should be a small indent on roughly the centre of each pad, any pins not making contact will not have marked the chip pad.

if you have got a bent pin problem, (my mobo had entire rows wrong) then you have to fix it yourself, as bent pins are not covered under any warranty or RMA policy

In the end i purchased an Asus Ramapage III Extreme, cured the problem straight away