Help.

Daniel Insley · 24 Dec 2020 at 17:16

Last night I put my new 3080 into my pc and it's ran like a dream since. I've then turned the power on today and heard a pop from a new 1000w Corsair PSU that's been running fine for the last few weeks. Now when I try to start the pc everything fires up for a spilt second then turns off. I narrowed it down to the 8 pin CPU slot on the motherboard. I can't see any burn marks on the motherboard and I've tried a different PSU and it's still the same with that. I've only rebuilt this pc about a month and a half ago. Any ideas? And on a scale of 1-10 how ****** am I?
Corsair 1000w PSU, Asus tuf gaming OC 3080, Ryzen 9 3900X, Asus ROG x570 f motherboard and 32gb vengeance pro ram.

mickyflinn · 24 Dec 2020 at 17:30

If you think its the motherboard it mite be worth trying to reset the cmos and try booting with one stick of ram.

BUDFORCE · 24 Dec 2020 at 20:02

Any damage on the motherboard?

Have a good look, particularly for a failed capacitor, Google images for failed capacitor see if you can see the same on your motherboard.

Daniel Insley · 25 Dec 2020 at 00:14

Tried resetting the CMOS, no change. I had the motherboard out completely and couldn't see any damage. It still looks fresh out of the box.

MissChief · 25 Dec 2020 at 00:16

Daniel Insley said:
Tried resetting the CMOS, no change. I had the motherboard out completely and couldn't see any damage. It still looks fresh out of the box.

Try a basic, out of case build. One stick of RAM, minimal hard drives, if you’re using an NVME just use that and graphics card too. Put it together on the motherboard box.

Hakanese · 25 Dec 2020 at 00:20

when you say it starts up for a split second, do you clear bios startup? Friend had a psu that would power fans the lights then shut down. Have you a spare psu you can try out before you take everything out

Daniel Insley · 25 Dec 2020 at 00:20

MissChief said:
Try a basic, out of case build. One stick of RAM, minimal hard drives, if you’re using an NVME just use that and graphics card too. Put it together on the motherboard box.

Gave that a go earlier on. I stripped everything out of the case and had the bare minimum connected but still the same issue. I'm about to share a couple of videos to hopefully show exactly what is happening

Daniel Insley · 25 Dec 2020 at 00:24

This is with the 8pin removed. Everything seems to start up as it should https://youtu.be/cLmMt-UYYJA
This is with the 8pin in (I also tried with just the 4). it tries for a spilt second to get going then just switches off https://youtu.be/QCHqYoIx18I
It's only when the CPU 8 pin is in that I get this issue. I've tried a different PSU. Different 8 pin CPU cables. That's why I think it's the connection on the motherboard that's knackered even if it doesn't look like it has any visible damage

spolsh · 25 Dec 2020 at 08:19

Only use the 8 pin that came with the power supply. Any other models cable may have different pin layouts which can definitely blow something.

Can you smell anything odd from any part of the motherboard - even if no visible damage, sometimes there'll be a little whiff of "burnt" near a damaged part.

Daniel Insley · 25 Dec 2020 at 10:04

spolsh said:
Only use the 8 pin that came with the power supply. Any other models cable may have different pin layouts which can definitely blow something.

Can you smell anything odd from any part of the motherboard - even if no visible damage, sometimes there'll be a little whiff of "burnt" near a damaged part.

I've only used the cables that came with the psu. My Corsair PSU came with s couple of spare cables (the only change was when I tried my other PSU). I can't smell a thing. It's bizarre because there seems to be no damage at all. Could it be an issue with the CPU instead? I've checked that over and it looks fine. I haven't got a means to test it though on another board