Question Computer turns on for one second, then off then back on for good

Apr 9, 2020
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Hi,

I’ve purchased a 700w PSU to replace my 500w PSU, given the minimum rating for my graphics card.

I’ve plugged in all the relevant cables to my motherboard and double checked CPU cable, CPU fan connection etc but when I try and boot my computer it turns on for a second, then powers down, then about a second later powers on for good (but doesn’t boot). Seems like something to do with the capacitor in the PSU discharging; I understand that often this issue can be a bad connection with the 24 pin motherboard connector but have ensured the connector is properly seated. Tried reseating RAM, removing graphics card, resetting CMOS etc but no joy. Anyone got any suggestions?
 
Apr 9, 2020
5
0
10
0
Hi,

I’ve purchased a 700w PSU to replace my 500w PSU, given the minimum rating for my graphics card.

I’ve plugged in all the relevant cables to my motherboard and double checked CPU cable, CPU fan connection etc but when I try and boot my computer it turns on for a second, then powers down, then about a second later powers on for good (but doesn’t boot). Seems like something to do with the capacitor in the PSU discharging; I understand that often this issue can be a bad connection with the 24 pin motherboard connector but have ensured the connector is properly seated. Tried reseating RAM, removing graphics card, resetting CMOS etc but no joy. Anyone got any suggestions?
I also now get the same symptoms with the old PSU so suspect I may have burnt out the motherboard somehow. Is that likely?
 
Apr 9, 2020
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Yes.

What 500W did you have? What 700W did you get? Are they modular?

Clear the CMOS and try again.
Thanks, both Kolink. The 500w was not modular, the new one is.

Per original post have already tried resetting CMOS, no joy. Can now get it to power on from the get go but no beeps or display...
 
Apr 9, 2020
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Mobo's dead. the new PSU probably killed it.

Was asking about modularity because sometimes people mix modular cables and fry their stuff that way.
Ok, thanks. If I buy a new Mobo any tips on how I avoid the same thing happening again? Is the PSU therefore faulty?
 

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