Konig CMP-PSUP550W is it any good or has it fried my MBs?

About a month ago I bought a PSU (make and model in the subject line) after my very old PSU nearly burned. Within three or four weeks my computer froze. I managed to shut it down by holding the power button for four seconds. When I tried to start it again there was power to the fans, the standby led was lit (ASUS P4T-E motherboard) and the HDD made a brief sound like it was booting. Since there was no smell like something burned like when the first PSU fried out I thought my old motherboard had finally died. So I bought a new one with a new CPU and memory. When I booted up the computer it still acted the same so I took the 3-4 weeks old PSU to the shop where I bought it, they tested it, found out it was faulty and gave me a new one of the same brand and model. I tried my computer with the new PSU but it still behaved the same. I thought that the new one was faulty so back to the shop I went, this time the PSU tested okay. Next thing I tried was to use the PSU with my old MB and everything is the same. So now I want to ask if it is possible that the old Konig PSU has damaged both of my MBs even though there is no visible damage and smell?

Can I somehow check if my MBs are damaged?

It's fried.
I had an Antec 550 do the same thing and using it on RMA'ed MB did it 2 more times.

Never use a suspect PSU on a good MB to test it!