Question I swapped power cords between modular PSUs and now my computers won't run. Did I fry something?

[VeeQue]

My goal was to remove my Rosewill 750 W PSU from an existing build (Build A) and replace it with my Corsair 650 W from another build (Build B). Both builds powered on and ran prior to this (Story spoiler: they don't anymore).

I plugged a CPU 8 pin cord from my 750 into my 650, which I later learned not to do since they have no set standard. Live and learn and break things, I guess.

Clues:

• I had heard a click in the 650 W PSU when attempting to power it on inside Build A, but nothing more.
• I did a paperclip test on the 24-pins respectively and both PSUs fans started running.
• I believe I plugged everything to the motherboard properly.
• I put both PSUs back into their original builds and neither powered on.
• I heard a slight buzzing in the 750 PSU when I tried to power it on inside Build A.

So. How bad is it, doc?

 

[siaan312]

Sad to tell you, but the psu is likely fried.
I believe the rest of the machine should be okay though.

The fans could still be spinning since they are not using the fried 12V rail on the PSU.

If anything did fry, it would probably be only the mobo.

 

[VeeQue]

Sad to tell you, but the psu is likely fried.
I believe the rest of the machine should be okay though.

The fans could still be spinning since they are not using the fried 12V rail on the PSU.

If anything did fry, it would probably be only the mobo.

So you're saying the PSU + motherboard are toast? Or just the motherboard?

 

[sonofjesse]

never mix brands, some brands you can't even mix (different series), this question comes up a lot.

If you have a friend who can help with extra parts you can troubleshoot what is bad.

 

[DSzymborski]

So you're saying the PSU + motherboard are toast? Or just the motherboard?

There's no way to know without testing the parts. CPU, motherboard, and PSU are certainly the likeliest things to be destroyed.

If the PSU doesn't work on the unaffected machine with all the correct parts -- assuming you didn't use the wrong cables there, too -- then the PSU is likely dead. The question then goes to whether the CPU and/or motherboard are fried.

 

[VeeQue]

There's no way to know without testing the parts. CPU, motherboard, and PSU are certainly the likeliest things to be destroyed.

If the PSU doesn't work on the unaffected machine with all the correct parts -- assuming you didn't use the wrong cables there, too -- then the PSU is likely dead. The question then goes to whether the CPU and/or motherboard are fried.

Solid, I appreciate the response. Got a fresh PSU flying in and I've got another AM4 motherboard just laying around, so I'm good and ready to give it another go.

 

[DSzymborski]

Solid, I appreciate the response. Got a fresh PSU flying in and I've got another AM4 motherboard just laying around, so I'm good and ready to give it another go.

Save yourself time and simplify the problem by breadboarding the build outside of the case on a non-conductive service like the box the motherboard comes in.

 

[ohio_buckeye]

What version is the other board? You may run into issues with bios updates if you have to use it unless you’ve got an older version ryzen cpu around. Assuming your current cpu is zen 2 or 3.

 

[siaan312]

Solid, I appreciate the response. Got a fresh PSU flying in and I've got another AM4 motherboard just laying around, so I'm good and ready to give it another go.

Great, also, what I meant before was that the PSU is most probably toast, your motherboard should be find though.
Your CPU is very unlikely to die from this since they have all sorts of protections nowadays.

 

[VeeQue]

What version is the other board? You may run into issues with bios updates if you have to use it unless you’ve got an older version ryzen cpu around. Assuming your current cpu is zen 2 or 3.

I'm not using a Zen, it's a Ryzen 9.

 

[VeeQue]

Save yourself time and simplify the problem by breadboarding the build outside of the case on a non-conductive service like the box the motherboard comes in.

Got any good videos on that? Sounds pretty straightforward, but I don't want to take any risks at this point.

 

[DSzymborski]

I'm not using a Zen, it's a Ryzen 9.

Thats's a Zen.

 

[VeeQue]

Great, also, what I meant before was that the PSU is most probably toast, your motherboard should be find though.
Your CPU is very unlikely to die from this since they have all sorts of protections nowadays.

Well, that's something to be optimistic about
If it's toast, I'll take the L, but if it's still good, I'll save a few bucks. Thanks for the reply.

 

[VeeQue]

Thats's a Zen.

Wonderful, looks like I own a Zen 💯

 

[ohio_buckeye]

I'm not using a Zen, it's a Ryzen 9.

Zen is the series. Example a 1000 series is zen 1. 2000 series was zen +. 3000, zen 2. 5000 zen 3, Now on socket am4 with the 7000 series they are at zen 4.

The acronym for ryzen 3,5,7 or 9 for example is the class of cpu, similar to the i3, i5, i7, i9 and so on.

But anyway, depending on how old your other board is, if it were say a b350 or b450, you might need an older 1000 series cpu to update the bios. Like my board is a b350 from about 2017 or 2018, but it started out with a ryzen 1600. But now I run a 5800x in it after all the bios updates.

 

[siaan312]

Got any good videos on that? Sounds pretty straightforward, but I don't want to take any risks at this point.

Almost every PC build guide uses this "system"
Just put your mobo on a piece of cardboard (Usually the box it came in, but it doesn't have to be), and then connect everything to it.

 

[NaClKnight]

I'm not using a Zen, it's a Ryzen 9.

All AMD Ryzen CPUs are Zen.

Zen +/2/3/4 is used to indicate the technology inside the processor process it was made with. So a Ryzen 5 5500 can still be Zen 2 even though the Ryzen 5 5600 is Zen 3

Ryzen 3/5/7/9 is used to indicate the expected level of performance. This doesn't tell you anything about the generation of technology/process used to actually make your CPU. A 2600, 3600, 5600, and 7600 are all Ryzen 5 but have different internal structures.

I may have some of the minor technical details wrong but that's the basic concept

 

[VeeQue]

Thank you all for your assistance, you've been a solid help! Got some great news, I got a couple of PSUs and used them to breadboard my previous builds (making quite sure not to mix the cables, haha).
Both turned on successfully, and I tested the components with OCCT. During a CPU stress test, the software showed all 24 cores firing at 100%, and the GPU ran perfectly. I only ran the tests for a few minutes and plan to go back in there for round 2.

So now we've got a couple more questions on the agenda:
A. The CPU and GPU both outwardly appear to be operating nominally. What should I be testing for damage, and how do you recommend I best test them?
B. How should I best test my previous PSU for damage?

Thanks again guys, it's been a surprisingly fun process. Any more help would be icing on the cake, but who doesn't love a little icing?

 

[VeeQue]

What version is the other board? You may run into issues with bios updates if you have to use it unless you’ve got an older version ryzen cpu around. Assuming your current cpu is zen 2 or 3.

Btw, spare motherboard is a Gigabyte B550 Gaming X, thoughts?

 

[ohio_buckeye]

B550 should be ok.

 

[siaan312]

Btw, spare motherboard is a Gigabyte B550 Gaming X, thoughts?

A good value board, nothing wrong about it.

Thank you all for your assistance, you've been a solid help! Got some great news, I got a couple of PSUs and used them to breadboard my previous builds (making quite sure not to mix the cables, haha).
Both turned on successfully, and I tested the components with OCCT. During a CPU stress test, the software showed all 24 cores firing at 100%, and the GPU ran perfectly. I only ran the tests for a few minutes and plan to go back in there for round 2.

So now we've got a couple more questions on the agenda:
A. The CPU and GPU both outwardly appear to be operating nominally. What should I be testing for damage, and how do you recommend I best test them?
B. How should I best test my previous PSU for damage?

Thanks again guys, it's been a surprisingly fun process. Any more help would be icing on the cake, but who doesn't love a little icing?

If they can complete a 100% load stress test (Prime95 for extra stability, it's a power virus stress test) for a prolong period of time (say, overnight or 24 hours.)
They are probably 100% okay.

As for how to test the previous psu, just connect it to your system with the correct cables and check if it can handle a gpu and cpu load and if it boots at all.