[SOLVED] PC unable to boot with 8pin CPU connected

Jun 9, 2021
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I've read multiple posts about this but can't seem to pinpoint the solution.

My PC (few months old) suddenly was unable to boot after I forced off it using the wall plug.

I've unplugged everything and pin point the problem to either the motherboard/CPU. I have replaced all cables and PSU to a newly purchased one.

When I connected the 8pin CPU plug (leaving the 24 pin on) everything on my motherboard powers, but there's no light to my keyboard and mouse and also no display. When I plugged in the 8pin, nothing powers on.

I have switched to another motherboard, and this time with the 8pin CPU plugged, I get everything lighted on the motherboard, but still no display/power to my keyboard or mouse.

Wondering if this could mean my CPU is fried? Any help is appreciated. Thanks in advance!
 
Solution
Sorry, I do not have the old keyboard to try it with. Even if it did work I'm guessing there's still some problem which prevents the display on my monitor from showing?

For your case, not much, as you don't have a built-in video (that's whyI hate motherboard without integrated video).

In old time when I see the PS/2 doesn't come on for mouse and keyboard, it's usually a sign of grave PSU issue. An ATX power tester is required to see what happens.
Only the RAM sticks (i've tried removing them already and same thing happens), 24 pin connector, front panel connector, and CPU 8 pin plugged in.

If you motherboard has no PS/2 connectors, it could also be a problem with the USB ports.

Did you try all USB ports?

Another thing you may need to do is to reset the Bios (by removing the battery or shorting the CRT_CLR pins.
 
Jun 9, 2021
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If you motherboard has no PS/2 connectors, it could also be a problem with the USB ports.

Did you try all USB ports?

Another thing you may need to do is to reset the Bios (by removing the battery or shorting the CRT_CLR pins.

Thank you for replying.

Yeap, all usb port had no power. No display to my monitor too.

I've tried resetting the BIOS too, by removing the battery.

Unfortunately, I don't have another CPU to test further. I am using AMD Ryzen 5 3600 if it helps.
 
Jun 9, 2021
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That CPU doesn't have built-in video, so you won't get any video output.

What video card do you have ?

I see. I didn't know that. Tested the display on the motherboard output and got nothing.

However, the display output on my RTX 2060 has no results too.
 
Jun 9, 2021
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Can you take a clear photo of your PSU and its cable connectors?


If you tested the same PSU and CPU on two motherboards, you should find a way to test the PSU's 8-pin (for CPU) and the 24-pin main connector to make sure none is faulty.

Thank you so much and I apologise for taking your time.

The connectors are all new together in the box of my newly purchased PSU. I swapped out my GPU with my old GTX 960 and still no display. I think the CPU is connected well as I can feel it being hot (no burning smell) after some time.

The lack of lights on my keyboard + mouse and no display seems to indicate that it is a CPU problem. I am honestly stuck now and considering purchasing a new CPU. I have already contacted AMD for RMA of my CPU.
 
Jun 9, 2021
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Can you take a clear photo of your PSU and its cable connectors?


If you tested the same PSU and CPU on two motherboards, you should find a way to test the PSU's 8-pin (for CPU) and the 24-pin main connector to make sure none is faulty.

View: http://imgur.com/a/FvugHN5


Maybe to add on, it's not a newly built PC. This suddenly just happened yesterday morning after using it for a few months.
 
Just to be sure:
  1. you do not specify the new (2nd one, the "other motherboard") motherboard you use (sure that the bios is compatible with the 3600, and not an old mobo with an old bios only compatible with 1rst gen Ryzen)
  2. why did " I forced off it using the wall plug. " happened ? Was is accidentally, or did you have to switch off like that because the PC froze ?
 
Jun 9, 2021
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Just to be sure:
  1. you do not specify the motherboard you use (sure that the bios is compatible with the 3600, and not an old mobo with an old bios only compatible with 1rst gen Ryzen)
  2. why did " I forced off it using the wall plug. " happened ? Was is accidentally, or did you have to switch off like that because the PC froze ?

1. The motherboard I was using was a B450, the BIOS was compatible. The one I am currently testing on is a older model, AORUS AX370. The bios is probably not compatible but I can't get any display at all during testing.

2. The reason I forced off the switch was because I was originally able to boot (on my B450) but there was no display on my monitor. I thought it was just a glitch, so I forced off the main plug. I then tried to turn it on but it no longer booted. I have a few suspects: my room is very humid and air conditioned, might have cause condensation in the rig. Also, I was running 2 games the night before, might have overstressed the CPU?
 
Jun 9, 2021
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Your motherboard seems to have at least one PS/2 connector, do you have any old keyboard to use with it?

The PS/2 connector should work even if the USB ports don't.

Sorry, I do not have the old keyboard to try it with. Even if it did work I'm guessing there's still some problem which prevents the display on my monitor from showing?
 
Sorry, I do not have the old keyboard to try it with. Even if it did work I'm guessing there's still some problem which prevents the display on my monitor from showing?

For your case, not much, as you don't have a built-in video (that's whyI hate motherboard without integrated video).

In old time when I see the PS/2 doesn't come on for mouse and keyboard, it's usually a sign of grave PSU issue. An ATX power tester is required to see what happens.
 
Solution