The firewire sockets in the back of the H8000 seem to permit upside-down insertion of the Firewire cable (male), which I now suspect is what is frying the chips. Anyone still using FW should take extra care when connecting.
The sockets are polarized, so you have to use some force to get it the wrong way round. But, once you have succeeded it will be easier the next time.
Look at the grounding, also. Best to plug the H8000 into the same outlet as the computer.