I really wonder however, how you manage to have THIS many hardware failures?!
Easy:
1) He's got a lot of hardware, and plenty of hardware is shipped faulty. So it's numbers
2) He's stressing the hardware, mining really puts hardware through it's paces, and quite a bit doesn't make it.
1) I don't consider 15 mainboards "a lot" - and there were more than 1 DOAs amongst them, reportedly. I don't even blame tawsix for anything, it's just very strage, that the hardware failure rates seem through the roof to me and far above anything I would expect.
2) Then he does something wrong - as he won't disclose exact specs, one can only speculate (no pun intended...). Might be for example a too cheap PSU model that is running too hot or something else like a simple BIOS switch or whatever.