Tricky computer hardware question:

orbital · Mar 5, 2020

+

I'm using an old system I dusted off to ask this,

Was having some flaky freeze-ups on my main computer, so a few nights ago I replaced an old Seasonic 750 gold rated power supply.
It was nearly 10 years old & I had a brand new 750 'gold rated' EVGA on the shelf, so I installed that.

I go to turn on my system & got nothing,, zero
Looking carefully at everything (and everything looked good on install) I decided to put my old functioning Seasonic back in.
Went to power up & got NOTHING again!!!!!!!

What a headache, I decided it was the power switch on the case,,,,,,, so I rebuilt my on entire system into a new Coolermaster case.
Using the new EVGA power supply, went to power it up & got nothing again.

Now I'm in total disbelief, what can it be,,, now I decided it was the motherboard, right?

Last night I was thinking about this, what if it's the PSU?
So I googled what to do on testing a PSU (I'm fine w/ using mulitmeters, jumper pins ect)

I carefully tested each PSU & both PSUs' were now dead, one that was actually running fine & a brand new one :caution:

Can a motherboard kill a PSU & if so, how??

thanks~~

archimedes · Mar 5, 2020

I suppose a short could destroy most anything, but I think that would be pretty unlikely. Especially if it was working before and "nothing happened" (no ESD, no metal shavings got into the case, the box wasn't dropped or fell over, etc, etc)

PSU are notoriously flaky though, and can go bad suddenly without warning, at any time.

Were both PSU older units ? Had the "new" (old? ) one definitely worked properly before ?

orbital · Mar 5, 2020

+

the original Seasonic was in my working system when I shut down, to install the EVGA (Seasonic had a decade on it)
the brand new EVGA was still factory sealed (G2 model about a year old)

both are now DOA

..no metal shavings in case or anything like that, I'm rather particular about my things

archimedes · Mar 5, 2020

Connectors should be "only fits one way" types with asymmetrical plastic channels and such ... everything fit easily, no cracked casings or bent pins, etc ?

Is the PSU rated as adequate for the load from your system ?

Do you have a powerful graphics card or other high load devices ?

I know you said you tested both PSU but did you happen to check the cables too ?

I've had a surprising number of cables go bad, and for some reason that often seems to be the last thing I ever consider.

vadimax · Mar 5, 2020

If you have a DMM — check the output voltages of power modules. If those are OK, your motherboard is gone.

You won't believe, but old systems may die just because you have moved them from one table to another.

archimedes · Mar 5, 2020

Was the computer/PSU plugged into some sort of surge suppressor ? Do you have relatively "clean" AC power ?

orbital · Mar 5, 2020

+

- everything plugged in correctly
- 750W is more than enough for my components
- tested the older & brand new cables
- on a sure protector powerstrip originally powering up both PSUs'
- I have very good AC power in my area

goes without saying, I just don't want to roach another PSU.

archimedes · Mar 5, 2020

Warranty on the EVGA ?

Maybe contact them to see if they would take a look at the new/failed unit ?

Always occurs in retrospect, but would have been nice to know (confirm) if the new PSU was working prior to installation ....

I have had any number of new-in-package electronics parts be nonfunctional.

archimedes · Mar 5, 2020

I still think that of these two scenarios ...

1) Failing old PSU, swapped for new (defective) PSU, swapped back to (now failed) old PSU

2) Some other problem, working old PSU swapped for brand new PSU (destroyed by mobo) , swapped back to old PSU (also now destroyed by mobo)

... the former is much more likely :shrug:

orbital · Mar 5, 2020

^

thanks for your time arch..

archimedes · Mar 5, 2020

orbital said:
^

thanks for your time arch..

Certainly, cheers.

I enjoy troubleshooting in a way, as a kind of puzzle or challenge.

But not so much for my own stuff, that's not such fun, I know.

Anyway, sorry, and glad to try to help.

Lynx_Arc · Mar 5, 2020

First todays power supplies you can't just "test" them without doing a little work I think you have to either short across some wires or put a load on it to get it to work without the power supply detecting a circuit board properly it won't do anything at all I believe.
Second, I had a computer that wouldn't do anything and it ended up being a bad memory module I didn't even get a beep until I took both modules out and then tried one then the other and figured out which one was bad.

archimedes · Mar 5, 2020

Two good points above ....

There are specialized PSU testers available, and I don't believe that they are especially costly.

Bad RAM can cause all sorts of weird problems. One standard troubleshooting procedure involves trying to boot an extremely limited system - remove all but one stick of RAM, rely on onboard graphics (remove video cards etc), basically unplug and remove anything not absolutely needed for POST. If that doesn't work, swap for a different stick of RAM and try again.

I've even had a USB peripheral that when plugged in at power-on would prevent proper booting. Worked fine when connected AFTER boot, but not before :crazy:

ColdZero · Mar 5, 2020

Are you using the same power cable from your wall outlet to both power supplies ? Could that be the issue ?

orbital · Mar 5, 2020

+

RAM..[]
Didn't mention this in my op; before I even swapped out the PSU, my first troubleshooting was replacing the RAM w/ modules I knew worked fine.
=used the 'B' DIMM slots as to change= system was running normally.
excellent points above regarding RAM
_________________________________________________________________________
Still thought PSU change would be a good idea 'cause I had an extra.

Test: I jumped the 24 pin green & black from the psu, had a fan plugged in, turned on power.
No voltages, nothing at all.

Tested both power cables on each

I'v been tryin'

Lynx_Arc · Mar 5, 2020

Maybe you blew the fuses in the power supplies, it looks like they aren't simple to replace though if they have one probably soldered in.

orbital · Mar 9, 2020

+

So on Sat. night I nearly tripped over a box at my back door taking the dog out,, FedEx on Sat.)
wasn't expecting my new psu.
The new evga psu came w/ a jumper tester,, helpful to test psu straight away.

I was in nearly a unhealthy place on how careful I was on my build,, just weary of the onset headache possibility.
Even gave it a whole day before I plugged-in & gave it a go.

OK, everything plugged in and I hit power on my case, nothing, duhhh turn on the psu :poke:

:laughing:
I turn on & get a long beep followed by a long beep
Swapped out different RAM into the original slots,, had to reset timing in bios & I'm typing on my original system now.

There had to be a short on my other case, frying my PSUs'
thing is, it was not a cheapo case.

What a nutso journey, but I take pride in my builds

archimedes · Mar 9, 2020

Thank you for the update, and glad you got it sorted [emoji106]

I've seen something like that happen with a tiny dropped screw inside the case (not saying that was the situation here, simply an example)

raggie33 · Mar 15, 2020

orbital said:
+

I'm using an old system I dusted off to ask this,

Was having some flaky freeze-ups on my main computer, so a few nights ago I replaced an old Seasonic 750 gold rated power supply.
It was nearly 10 years old & I had a brand new 750 'gold rated' EVGA on the shelf, so I installed that.

I go to turn on my system & got nothing,, zero
Looking carefully at everything (and everything looked good on install) I decided to put my old functioning Seasonic back in.
Went to power up & got NOTHING again!!!!!!!

What a headache, I decided it was the power switch on the case,,,,,,, so I rebuilt my on entire system into a new Coolermaster case.
Using the new EVGA power supply, went to power it up & got nothing again.

Now I'm in total disbelief, what can it be,,, now I decided it was the motherboard, right?

Last night I was thinking about this, what if it's the PSU?
So I googled what to do on testing a PSU (I'm fine w/ using mulitmeters, jumper pins ect)

I carefully tested each PSU & both PSUs' were now dead, one that was actually running fine & a brand new one
Can a motherboard kill a PSU & if so, how??

thanks~~

i quit building pc,s years ago hect my ipad is more powerful then my last pc lol hect i think my last pc also pulled like 250 watts from the outlet lol

orbital · Mar 30, 2020

archimedes said:
Thank you for the update, and glad you got it sorted [emoji106]

I've seen something like that happen with a tiny dropped screw inside the case (not saying that was the situation here, simply an example)

+

I don't mean to be bumping this thread, but a quick update2.0

The reason I even bothered w/ swapping out my psu is I was getting odd random crashes, bluescreens ect...
you never really know if it's software or hardware,, really it can be an endless troubleshoot/search

After everything done on rebuild after rebuild (including a brand new psu being DOA)______ I have not had a single crash w/ my system :grin2:

So it was in fact the original psu failing all along.

Thanks for everyones' posts

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