What about the change in the CPU cooler? You are mentioning the cable management you did, but you also did the change of the cooler at the same point in time, right? Never seen the new cooler run without the cable management changes you did?
I'm thinking it might be something funny happening with the socket and socket pins and the board flexing differently with the different coolers and their different pressure.
Well I don't tighten it any more than it allows. It always seems like these retention systems know when to stop. Except the Hyper212+, I actually think I tightened that more than I did with this CLC because it didn't stop me from screwing the screws in as early from what I remember. But I am not using much strength either, I don't want to crack or break the CPU, so Idk. At first I tried putting the CM Seidon 120M backplate on with the mobo still screwed on, but it was impossible. So I unscrewed the mobo a bit, attached it and screwed it back on. But since then I've took the whole motherboard out and re-seated it.