Another thing is that the second board also got as warm as the first. If it weren't hashing wouldn't it be noticeably cooler?
H@shKraker
Spending some time tuning my frequency and voltage this evening, I found it's easy to get a board into a bad state by excessive overclocking and/or excessive overvolting (and you're doing both to the extreme). Once it gets in this state, I see exactly what you do.... the board will not hash (yellow light flashes but no activity on the red light) until it is power-cycled.
I'd suggest that to start with, you don't overclock or overvolt at all. Use a frequency of 256 and a core voltage of 900mV and see how you get on. Even that should give you a higher hash rate then you're getting at the moment.
Then, once you've got it stable, gradually increase the frequency. You might not be able to go much above 265. Overvolt the minimum necessary to get hardware errors down to an acceptably low level (I have to overvolt even at 256). Also, I find you need to leave it running for an hour or so to get a realistic picture of what's going on, as the hw error rate starts off high and then drops.