Had an issue where system would not POST if there was RAM installed in the first 2 RAM slots (A1/A2 closest to CPU). System posts fine if RAM is in either or both of the other slots (B1/B2 furthest from CPU) So I thought the RAM was bad somehow or possibly the motherboard (didn't have another board at the time to test) so I tried other sticks and got the same issue. Tried swapping out other various components and got to the point where I confirmed CPU, RAM, GPU etc worked in another setup. So I assumed the motherboard was bad but after swapping that out I still had the same issue. The only common parts I was still using were are cables and HSF which ended up being the culprit. I'm using a Coolermaster 212 and I read on some other posts about the cooler being tightened too much/incorrectly possibly causing problems with the standoffs being too tight effecting the traces on the board. In my situation the tightness of the cooler to the standoffs wasn't effecting the tightness between the motherboard bracket/support. I went back and made the tightness between the standoffs/bracket hand tight and now the system boots/runs with no issues. Just posting this so that it might save some people hours of troubleshooting time!