You can damage hardware components depending on what happens inside the power supply during a short or other type of fault. Example: my IWILL ZMAXDP -- I had a molex connector with a high resistance connection that blew my proprietary power supply. After I fixed the power supply, the machine wouldn't boot anymore. When the power supply popped (literally), it also took out both Opteron CPU's with it. Luckily, replacing the CPU's brought the system back to life with no other issues.

I have never ever heard of a fan connected the wrong way kill a motherboard or a PSU.

Some Dell Optiplexes had 4 pin fan connectors that... had switched wiring. So stupid.

Seems unlikely to me. I've outright shorted +12v to Gnd before on PSUs. Older ones (before people thought they needed a kilowatt of power in something left on the floor within inches of their feet) would just shut down from over-current protection. Newer ones (with dozens of amps on the 12v rail) will gladly destroy whatever you used to create the short. The motherboard may or may not have a polyfuse in series with the fan header for this reason -- sometimes fans fail, and sometimes they fail short. (Or at least stall and become low impedance -- depending on the motor topology.)

Does your PSU tester load the supply? It could just be out of spec under a zero-load condition. If it's in-line between the PSU and motherboard, then it should be accurate, and maybe your PSU was just ready to go toward the light.

SirNickity wrote:

Does your PSU tester load the supply? It could just be out of spec under a zero-load condition. If it's in-line between the PSU and motherboard, then it should be accurate, and maybe your PSU was just ready to go toward the light.

When I saw those voltages, I was seeing them through SpeedFan while the system was on. The PSU tester was saying that there was no -12v at all- SpeedFan was saying that there was -3v on it.

athlon-power wrote:

SirNickity wrote:

Does your PSU tester load the supply? It could just be out of spec under a zero-load condition. If it's in-line between the PSU and motherboard, then it should be accurate, and maybe your PSU was just ready to go toward the light.

When I saw those voltages, I was seeing them through SpeedFan while the system was on. The PSU tester was saying that there was no -12v at all- SpeedFan was saying that there was -3v on it.

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Never trust software voltage readings. Your system would likely not even boot with those voltages.

appiah4 wrote:

Never trust software voltage readings. Your system would likely not even boot with those voltages.

How would I put the PSU under load while the PC is off? Maybe I could try and connect a couple of HDDs or something like that.

That's the cheap and easy way, but it won't put much of a load on it. Usually "enough" so older PSUs that require a minimum load will power on and stay running, but it isn't really a good way to stress-test a supply. For that you need a substantial load. Common solutions include big fat high-wattage resistors, incandescent bulbs, active load test equipment, etc..

I'm not getting a good visual image of what your PSU tester is or does. Is it just a cheater plug to turn on an ATX supply, or does it do something else?

I'll agree software voltage readings are dubious, though usually when I see one that's obviously off, there's a reason for it. (E.g., it may be showing something weird on a -5V line with a PSU that doesn't provide that rail -- so it's just floating.) YMMV. Get a voltmeter and try to probe the back of the ATX connector while it's plugged in to the motherboard and powered up. Be careful poking around, and make sure you check the pinout so you know what you're measuring.

Also, 2.3V on the battery seems questionable. Dead coin cell, or just a bum sensor?

SirNickity wrote:

I'm not getting a good visual image of what your PSU tester is or does. Is it just a cheater plug to turn on an ATX supply, or does it do something else?

Here's a couple of pictures of it, one of it off and one of it on.

It's still saying there's no -12v. Compare this to when the exact same connectors (1x SATA, 1x 6-Pin, 1x4-Pin, Motherboard connector), are connected to my Corsair TX650W from 2008:

Compare it to this other 300w Dell PSU I have, it doesn't have a 6-Pin connector, but everything else is the same:

And finally, compare it to this 150w Dell PSU, also without a 6-Pin connector, but everything else is the same:

That's absolutely bizarre, but the only explanation I can think of is that when connecting the fan you shorted the 12V rail and possibly the transformer at the end of the 12V rail went tits up inside the PSU so now you have no -12V?

I'm inclined to chalk this up to a coincidence or a PSU that was getting ready to check out anyway.

A common topology is to have a single trafo with multiple windings. It's group-regulated because you can only control the PWM from the rectified AC through the trafo, and the outputs all share the same magnetic flux, so a load on one rail will affect ALL rails minus some degree of error due to impedance in that rail. In this case, I can't see a failure mode that explains what you saw.

An alternative, since the neg rails are usually half an amp at best, is to use a switching inverter from one of the main rails (probably +12V). That one has SOME of the path in common, so potentially COULD have suffered damage, but it still doesn't seem very plausible to me.

Really the only thing that makes any sense is if the monitoring circuit got hit somehow and is doing something stupid. Curious.

SirNickity wrote:

I'm inclined to chalk this up to a coincidence or a PSU that was getting ready to check out anyway. […]
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I'm inclined to chalk this up to a coincidence or a PSU that was getting ready to check out anyway.

A common topology is to have a single trafo with multiple windings. It's group-regulated because you can only control the PWM from the rectified AC through the trafo, and the outputs all share the same magnetic flux, so a load on one rail will affect ALL rails minus some degree of error due to impedance in that rail. In this case, I can't see a failure mode that explains what you saw.

An alternative, since the neg rails are usually half an amp at best, is to use a switching inverter from one of the main rails (probably +12V). That one has SOME of the path in common, so potentially COULD have suffered damage, but it still doesn't seem very plausible to me.

Really the only thing that makes any sense is if the monitoring circuit got hit somehow and is doing something stupid. Curious.

My question is, with the PC having been able to boot just fine, do you think my motherboard got damaged at all, or for that matter, any of my components, or did the PSU just scream in agony and try to die? I'm going to replace the PSU with a nice 80+ Gold ~500w PSU once I get my paycheck.

I can't even really explain what happened, so it's hard to tell. The negative rails aren't used for all that much anymore, so it's likely your PC wouldn't have noticed their loss. But if something damaged the PSU via the motherboard, then it possibly took damage along the way.

You mentioned having hooked up the other PSU and your PC POSTed OK. Did you check the voltages that way? (Can you? You mentioned it doesn't have one of the 12V connectors...) I'm curious whether your good PSU would show healthy voltages via the motherboard sensors, or if it may be the motherboard pulling them out of spec on your bad PSU -- indicating maybe the PSU isn't what went bad.

So, if you do power it up OK and the voltages look normal, I would expect it to be fine, but there's only one way to find out...

SirNickity wrote:

I can't even really explain what happened, so it's hard to tell. The negative rails aren't used for all that much anymore, so it's likely your PC wouldn't have noticed their loss. But if something damaged the PSU via the motherboard, then it possibly took damage along the way.

You mentioned having hooked up the other PSU and your PC POSTed OK. Did you check the voltages that way? (Can you? You mentioned it doesn't have one of the 12V connectors...) I'm curious whether your good PSU would show healthy voltages via the motherboard sensors, or if it may be the motherboard pulling them out of spec on your bad PSU -- indicating maybe the PSU isn't what went bad.

So, if you do power it up OK and the voltages look normal, I would expect it to be fine, but there's only one way to find out...

I should probably change the name of this post to "Killed My Main PC," because that's exactly what I did. I tried that 650W Corsair PSU, and the motherboard gave the exact same screwed readings as it did with the other PSU. When I use that same software on my 2008 PC, it shows the voltages are just fine.

So it damaged something on the motherboard and something on the PSU. My question is, is the processor salvageable? It's a Ryzen 5 2600, and as I said, the system POSTs and boots just fine, but I feel like that doesn't mean some component somewhere on that CPU wasn't fried during that little "excursion".

If the computer boots and the motherboard is stable, I'd keep using it to be honest.

Maybe use a different PSU from now on, but the motherboard is probably just fine to continue being used.

Does that PSU tester pass through to the motherboard? I.e., when you tested the "bad" PSU, was it plugged in to the tester, and on to the motherboard as well? My thought here is that maybe the PSU isn't bad -- the motherboard's just dragging those rails down and putting the PSU into current limit. That isn't great, because the PSU would basically always be in protect mode and maxing out its negative rails. But, TBH, I would do the same thing -- just run the board and the "bad" PSU until one or the other quits.

It's kind of just a theory, because I don't know off the top of my head how typical modern PSUs handle the neg rails. If it's an inverter or a linear reg off a secondary winding, then it may be current limited instead of triggering OCP and shutting down. Or not. I am curious if the bad PSU would test OK when not driving that motherboard though.

SirNickity wrote:

Does that PSU tester pass through to the motherboard? I.e., when you tested the "bad" PSU, was it plugged in to the tester, and on to the motherboard as well? My thought here is that maybe the PSU isn't bad -- the motherboard's just dragging those rails down and putting the PSU into current limit. That isn't great, because the PSU would basically always be in protect mode and maxing out its negative rails. But, TBH, I would do the same thing -- just run the board and the "bad" PSU until one or the other quits.

It's kind of just a theory, because I don't know off the top of my head how typical modern PSUs handle the neg rails. If it's an inverter or a linear reg off a secondary winding, then it may be current limited instead of triggering OCP and shutting down. Or not. I am curious if the bad PSU would test OK when not driving that motherboard though.

No, the PSU hooks directly into the PSU tester, nothing goes between the PSU tester and the PSU. My problem with running the system until either dies is that I have a Ryzen 5 2600 I recently purchased in it- I don't want to risk damaging it.

My biggest thought now is questioning whether or not the Ryzen 5 2600 has been damaged in some form or fashion. Even though the PC POSTs and boots, I would suspect that a voltage spike could have damaged something inside the processor that I don't know about or would have difficulty finding on my own.

Processors now are incredibly complex, and I don't feel like it's the same as it was when an older processor died. If a 486 was dead, it was dead, and if it wasn't, it wasn't. Now, there's a gagillion little different components in them that could be damaged. I don't like the thought of building a new system from it in the worst case scenario if I don't know whether or not it's damaged.

athlon-power wrote:

Processors now are incredibly complex, and I don't feel like it's the same as it was when an older processor died. If a 486 was dead, it was dead, and if it wasn't, it wasn't. Now, there's a gagillion little different components in them that could be damaged. I don't like the thought of building a new system from it in the worst case scenario if I don't know whether or not it's damaged.

Run Intelburntest and prime95 for several hours each. If it doesn't crash, then stop worrying about it. If it was going to halt and catch fire, then it probably would have done so already.

My perspective is that you can never know if it is 100% factory perfect, only if it is stable and working correctly for the user workloads you can create. If you are worried, use a multimeter to check v-core as well while it is idle and at full load. About the only thing that really kills CPUs is excessive Vcore, so if the VRMs are working correctly and the system is stable under full load, there really isn't much more to test.

canthearu wrote:

Run Intelburntest and prime95 for several hours each. If it doesn't crash, then stop worrying about it. If it was going to halt and catch fire, then it probably would have done so already.

My perspective is that you can never know if it is 100% factory perfect, only if it is stable and working correctly for the user workloads you can create. If you are worried, use a multimeter to check v-core as well while it is idle and at full load. About the only thing that really kills CPUs is excessive Vcore, so if the VRMs are working correctly and the system is stable under full load, there really isn't much more to test.

Would it be a good idea to do that on the current motherboard I have? I wouldn't want to stress test the system and then have the motherboard or PSU really give out and fry the CPU, as well as all the other junk that's in it.