Question PC doesn't start after PSU upgrade

nb81

Honorable
Apr 13, 2013
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10,510
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Hi,

I bought a Seasonic Prime Ultra 750W Platinum PSU to upgrade my current build and replace my old Corsair TX550. PC ran fine for about 2 days, but then it stopped working. Power button doesn't seem to do anything (fans not spinning, status LEDs are all off). Put the TX550 back in and that got it to post.

While testing the Seasonic with the included PSU tester, the fan was spinning, so according to the manual it 'works'. Also checked voltages with a multimeter and everything matches the specs. It's almost as if the 5vSB pin was dead because the motherboard doesn't react to anything when I try turning it on. Tried reseting CMOS, no cigar. Mobo is an Asus Z390-E.

Any help is greatly appreciated.
 
Retail PSU testers do not test for all possible situations the PSU operates under, so it is not an entirely accurate indication of PSU status.

It seems most likely that the SeaSonic PSU is faulty. Return it for replacement (or refund?).
 

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