Question PC won't boot without jump-starting the 24pins cable

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Jeff_120

Jeff_120

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Dec 11, 2016
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Hello
Yesterday after installing a new PSU and GPU my PC won't boot up.
After 5 hours of troubleshooting with a PC hardware fan friend (who built dozens of PCs).
We unplugged everything then piece by piece reconnect, in the process I asked him to try jump starting the 24 pins cable, he did it using a PSU voltage tester, then he replugged the 24 pins right after to the motherboard and pressed on the power button : it booted like nothing happened ! Everything worked from cpu to gpu. But if we turned off the PC and PSU wait 4 minutes and try to boot the PC again...no joy
We tried several times, only jump start the PSU could let the system boot!!
Yes like a car that has a dead battery and you can but jump start it.
We tried:
-Replacing the cmos battery with a new one
-Testing with another PSU (it gave the same result as the new PSU)
-Update the Bios.
Well what to you think?
Is my Asus B550 Gaming TUF dead or zombified?
Or there is still hope?
 
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Jeff_120 said:
Hello
Yesterday after installing a new PSU and GPU my PC won't boot up.
After 5 hours of troubleshooting with a PC hardware fan friend (who built dozens of PCs).
We unplugged everything then piece by piece reconnect, in the process I asked him to try jump starting the 24 pins cable, he did it using a PSU voltage tester, then he replugged the 24 pins right after to the motherboard and pressed on the power button : it booted like nothing happened ! Everything worked from cpu to gpu. But if we turned off the PC and PSU wait 4 minutes and try to boot the PC again...no joy
We tried several times, only jump start the PSU could let the system boot!!
Yes like a car that has a dead battery and you can but jump start it.
We tried:
-Replacing the cmos battery with a new one
-Testing with another PSU (it gave the same result as the new PSU)
-Update the Bios.
Well what to you think?
Is my Asus B550 Gaming TUF dead or zombified?
Or there is still hope?
Click to expand...
Have you tried shorting the start pins on the 24 pin connector while it's attached to the motherboard to start the computer? You can also get at the pins from the backside of the connector with the paper clip to test it. If it boots like this then something on the motherboard or case switch is preventing it from working.

Have you tried shorting the "PWR_SW" pins on the motherboard to start it? If it boots like this and boots when shorting at the 24 pin then something in the case switch is preventing it from working.
 
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drea.drechsler said:
Have you tried shorting the start pins on the 24 pin connector while it's attached to the motherboard to start the computer? You can also get at the pins from the backside of the connector with the paper clip to test it. If it boots like this then something on the motherboard or case switch is preventing it from working.

Have you tried shorting the "PWR_SW" pins on the motherboard to start it? If it boots like this and boots when shorting at the 24 pin then something in the case switch is preventing it from working.
Click to expand...

Yes we tried all options
Jump starting pwr-swt didn't work, only jump start of the psu via the 24 pins cable
 
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Jeff_120 said:
Yes we tried all options
Jump starting pwr-swt didn't work, only jump start of the psu via the 24 pins cable
Click to expand...
That's making me think it's something on the motherboard then. If BIOS updates and CMOS resets (including battery change) can't help it's something in the hardware. The time delay could be a capacitor discharging (or not charging) as it should, possibly because it's failed and is leaky or through a leaky transistor junction. Pure guesswork to be sure but a reasonable possibility. Unfortunate but swapping the motherboard would be the next thing to try although swapping GPU, CPU then memory, if you have them, is easier just to rule them out first.
 
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drea.drechsler said:
That's making me think it's something on the motherboard then. If BIOS updates and CMOS resets (including battery change) can't help it's something in the hardware. The time delay could be a capacitor discharging (or not charging) as it should, possibly because it's failed and is leaky or through a leaky transistor junction. Pure guesswork to be sure but a reasonable possibility. Unfortunate but swapping the motherboard would be the next thing to try although swapping GPU, CPU then memory, if you have them, is easier just to rule them out first.
Click to expand...

We tested the Ram and it wasn't them that were blocking the boot.
As for the cpu , I could play Red Dead redemption 2 for 2 hours today (after jump start the psu) , I wonder if a bad cpu could load a game
 
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Jeff_120 said:
... I wonder if a bad cpu could load a game
Click to expand...
I'm considering it is in the startup sequence where it seems to be faulting. I'm not exactly sure that initiatilization circuits in a CPU could cause it to fault like this only during startup but they are kind of like the starter in your car: once it's started you can kick it to the curb and run all day long.

It's up to you if you want to try swapping out the CPU...if you can get one to do it with...to eliminate it as the problem. It's merely a suggestion because motherboard swapping for troubleshooting purposes is a PITA. And that's really what it seems to have come down to...and don't forget the GPU too.
 
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drea.drechsler said:
I'm considering it is in the startup sequence where it seems to be faulting. I'm not exactly sure that initiatilization circuits in a CPU could cause it to fault like this only during startup but they are kind of like the starter in your car: once it's started you can kick it to the curb and run all day long.

It's up to you if you want to try swapping out the CPU...if you can get one to do it with...to eliminate it as the problem. It's merely a suggestion because motherboard swapping for troubleshooting purposes is a PITA. And that's really what it seems to have come down to...and don't forget the GPU too.
Click to expand...

We tried 3 different GPU from very different models, all did the same.
As for testing the CPU , I don't have another M4 one, I will have to take my PC to a PC shop and let him try it, but he will charge me for the process.
I think the best but not cheapest way to be sure is to replace both MB and CPU
 
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Jeff_120 said:
And BTW why would the MB or CPU get a hardware problem as soon as I installed the new GPU and PSU?
Could one of these 2 gave an overvoltage and burned something in the MB?
Click to expand...
I can only guess...but it may be there was a latent defective component in the motherboard that the new GPU exercised heavier than the old one did, such possibly in the +12v filtering to the PCIe power socket which the GPU might use only at startup.

But at any rate, I wouldn't change both motherboard and CPU right off unless you're eager to upgrade CPU anyway. I'd go with a new motherboard, if it works then decide if you really want the new CPU. If it doesn't then go for the CPU since that's all that's left.

Oh and one other thing to do since it's easy and free: push on each wire at the 24pin connector to make certain that each of the socket contacts are fully engaged on the motherboard's socket contact. It's not uncommon for one of them to not engage fully even though the connector body is fully seated and clipped. This could cause strange problems.
 
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