Two dead PSUs in one day

[K1LLA_KING_KONG]

I am currently building / rebuilding two high performance PCs. One was totally functional with 750w cooler master PSU. The other brand new parts to assemble, with a 650w Corsair PSU

 

I swapped some from the already functional PC to the new case and mobo. 

 

End of the day I tried to fire both units up. And both dead. 

 

Both fail the 'paper-clip' test. I just head a tiny soft click-like noise. 

 

I tested the other pins with a multi meter (while the 'paper-clip' was bridging pins 4&5) and i get zero volts. 

 

Now one PSU was about 3 years old (the cooler master). The brand new corsair may be DOA. 

 

But its quite a coincidence that both dies at the same time. 

 

No i didn't do anything stupid like work on the PC while it was connected. All PC connections were 100% correct and fitted properly. 

 

Any idea what may have caused this? 

[An0maly_76]

Not unheard of, but don't some of these require a minimal load to actually start when testing?

Edited June 14, 2022 by An0maly_76
Revised, more info

[BetteBalterZen]

Did you somehow reuse any PSU cables? 

[An0maly_76]

9 minutes ago, BetteBalterZen said:

Did you somehow reuse any PSU cables? 

BBZ makes an interesting point. If modular, have you tested at the PSU pins?