Interesting problem with motherboard, any suggestions?

Not really a "help me fix it thread" but I wanted to ask a question about a motherboard I was working with lately, a friend built himself a pc with a Ryzen 5 2600, 2x4GB DDR4 vengeance LPX ram, a corsair VS550 and a Tomahawk B450 board. Once he tried starting it, nothing turned on, basically zero reaction. He checked for any problems on the motherboard itself then called me, we tried replacing everything, the psu, the ram and the cpu itself, still zero reaction and we tried 3 working PSUs. So with zero visible damage to the board and every other component working what could have been causing the no power problem? I told him to return the board on warranty and he did by now.

Post was last edited on June 23, 2019 7:21 AM PDT

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Did they?

Try it outside the case with bare minimum parts? Sometimes I find the build has shorted out the board in the case or forgot to check jumpers. A few boards won't power up with the CMOS jumper in its reset position.

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All was fine

Jumper was in the correct position, we took out the board and tested it when it was laying on cardboard, tried to boot it with only the RAM, CPU and GPU, then changed the ram, cpu and gpu to known working ones still getting nothing. We even tried removing the gpu altogether with the same result.

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Tackle "nothing turned on"

Power up issues point to motherboard failures a lot of the time. You don't need GPU, RAM and on many boards you don't need a CPU. For years we would have an old motherboard around just to do a power up test on PSUs. They didn't have the CPU installed.

Good to read the test was on cardboard. That shows they are using (good) advice here and on the web.

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I know that

I know that they point to motherboard problems but I wanted to ask why would an out of the box motherboard fail. I guess that it's just a manufacturing defect.

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For us that was rare.

You hear more about this in the retail sector. When I worked at my shop or elsewhere (long story) we had about one dead board a year and the seller would always admit it was a return.

So in 4 decades we had no motherboard failures that were direct from the factory. All appear to have gone out, been RMAd and resold, only to RMA again.

Now if you want to dive into why a motherboard doesn't power up, you would have to get into the schematic. Follow the signal that is on the GREEN WIRE of the PSU to where it goes on the motherboard and troubleshoot that circuit.

About 2 decades ago the makers stopped sharing schematics so you don't fix most motherboards. You replace them if the board is dead. Little things can be dealt with but not dead boards 99.9999% of the time.

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