The USB bit of my problem the other night was me having a blonde moment - was plugging the stick into chassis, when should have been plugging it into the board right in front of me on the desk
Anyway, the problem of it not recognising boot drive was 'just' that the boot loader got buggered, which was correctable using windows boot stick. Doesnt seem to have corrupted windows files like it had previously.
In the end, the only way to properly clear the bios was to flash it again...
But yesterday I decided to hell with it and ordered other ram. A corsair vengeance pro 32gb set.
Am now actually able to achieve 4.8 on the CPU! Even 4.7 was feeling a bit touch and go before, and just couldn't manage 4.8. 4.9 looks like it will take over 1.4v so not going there.
Also, couldn't even reach up to 950 score in ccinebench before, and now got up to 980.
Memory rated for 2133 at 11-11-11-31, but was happily running 2133 at 9-10-10-30.
So right now (and hope to god this is the case) it looks like this board maybe just didn't like the Kingston beast 2400 ram.
Currently only got 7770 gpu in, and once have done more stability testing, will throw my 3 290s in and fire up bf4