Hello!
A couple weeks ago I had a socket 1155 computer with i5 and an old 300W PSU. I decided to replace it with another working 400W noname passive Xilence PSU, because of the new videocard I installed (PSU calc showed me 320W max for my system). However, everything was okay with 300W during first try.
At second run (with new PSU), I forgot to put 4pin in it's place.
Then I saw that all fans are running, except there is no display signal. And that was it. At diagnostics they said me, that MAYBE due to wrong voltages, my motherboard ended along with the CPU.
Can PSU can kill motherboard and CPU at same time or problem was about forgotten 4pin?