Question No Power/System not starting unless CPU power cable is disconnected from the Motherboard

[Agoniyz]

Hello everyone,

I‘m slowly getting desperate, i‘ve spent countless hours searching the web and trying to find out what caused this.

I recently exchanged my motherboard for a new one (MSI MPG B550 Gaming plus AM4).

CPU is Ryzen 7 5800x

After the install - everything ran like butter and the PC was working well fpr about 1-2 days.

Yesterday I pressed the PW button and nothing happend, no lights, no fans nothing.

first I thought the PSU was faulty but I tested it with a paper clip and I even plugged it on another motherboard with the same CPU.

Worked fine.

So this is clearly a MOBO problem…thing is…itd brand new and it worked until it suddenly didnt.

Only thing I could notice when checking the cables was ou the little 4pin connector attached to the 20pin connector (AC power) not being insterted properly this whole time.

Unsure if that caused the Motherboard to fail…

Like the title says : Mobo runs aswell but ONLY when the 2x4 pin CPU power isnt connected

 

[Agoniyz]

Hello everyone,

I‘m slowly getting desperate, i‘ve spent countless hours searching the web and trying to find out what caused this.

I recently exchanged my motherboard for a new one (MSI MPG B550 Gaming plus AM4).

CPU is Ryzen 7 5800x

After the install - everything ran like butter and the PC was working well fpr about 1-2 days.

Yesterday I pressed the PW button and nothing happend, no lights, no fans nothing.

first I thought the PSU was faulty but I tested it with a paper clip and I even plugged it on another motherboard with the same CPU.

Worked fine.

So this is clearly a MOBO problem…thing is…itd brand new and it worked until it suddenly didnt.

Only thing I could notice when checking the cables was ou the little 4pin connector attached to the 20pin connector (AC power) not being insterted properly this whole time.

Unsure if that caused the Motherboard to fail…

Like the title says : Mobo runs aswell but ONLY when the 2x4 pin CPU power isnt connected

Id like to add: the white DEBUG LED is on (cpu) when the mobo seems like its running

 

[Dashhh]

Check the CPU for bent pins. This is a weird "one or the other" scenario. I'd imagine since you just bought a new board you'd be able to return it or have it repaired, but I would diag this some more. Are you getting any post beeps?

 

[Agoniyz]

Check the CPU for bent pins. This is a weird "one or the other" scenario. I'd imagine since you just bought a new board you'd be able to return it or have it repaired, but I would diag this some more. Are you getting any post beeps?

Thanks for your help brother,

No beeps no sound, all I get is a 0,5 sec red light from the MOBO.

 

[Agoniyz]

The CPU is also brand new by the way.

 

[Dashhh]

The 4-pin you're referring to, is that from the PSU? If that wasn't installed correctly then my brain goes immediately to an overvoltage issue that could have dinked your CPU or board over the course of the 2 days you had it operational.

 

[Agoniyz]

yes the 4 pin that is part of the ATX main connector. It wasnt clicked in lets say…

Your insight and the fact that everything ran ( CPU too) fine on the old MOBO - kinda confirms that the board is at fault.

Or am I missing something crucial here

 

[Dashhh]

Well, I don't feel like I have much information to go off of other than your system won't boot when the 4-pin is connected because it wasn't "clicked in let's say..." haha. When your system IS on without the 4-pin, are you able to get any logs or metrics from monitoring software or anything? Have you jumped into any of that?

 

[Agoniyz]

The system is „on“ (fans spin, led lights flash etc… ) when the 2x4 pin at the top left is disconnected. It doesnt boot obviously haha

That 2x4 pin was connected very fine. It was the 4 pin that is attached to the other 20pins that wasnt fully inserted.

I will try to link some pictures if I can

 

[Dashhh]

Do you happen to have an older CPU in the same chipset from an upgrade or anything? Is your PSU modular to where you can completely disconnect your cables?

 

[Agoniyz]

I have a Ryzen 5 2600x from my old build and the PSU is not modulr, the cables come with it.

its a bequiet Pure Power 10 600W

 

[Dashhh]

A few things. Both of those chips are AM4, so test your old CPU in the new board and see if you can boot with that installed. Second, can you list your full system specs? Not that I suspect this of an issue, but the 5800 has a max power draw of over 2 times that of the 2600. Pending your other hardware, a 600w PSU may play into this more than we might suspect. I'm curious at the very least.

 

[Agoniyz]

MSI MPG B550 Gaming Plus
Ryzen 7 5800x
CPU Cooler: Corsair H100 RGB 240mm
2x GB DDR4 RAM Kingston Fury RGB
GTX 1080 MSI AERO
1x Fan at the back
1x Fan at the front
Normally i have a 256gb SATA SSD plugged in and a Toschiba 1TB hard disk.

 

[Agoniyz]

I will try it with the older CPU in a bit. Thanks for your continues help ^^

 

[Agoniyz]

https://imgur.com/CrQltPP

View: https://imgur.com/CrQltPP

https://imgur.com/zMIzVyP

View: https://imgur.com/zMIzVyP

https://imgur.com/MP8YuZB

View: https://imgur.com/MP8YuZB

 

[Dashhh]

You're at about 500w with that build, so you have a little headroom as far as power consumption goes. Now, test that other AM4 chip and see if you can boot. If that works, we can at least narrow some things down. If that doesn't work, we'll try some other things.

 

[Agoniyz]

Alright, switched CPU.

Same thing haha

Cables that are currently plugged in : ATX Main connector, CPU fan and PW switch.

 

[Dashhh]

Did you change or configure anything in the BIOS after you put this new build together?

 

[Agoniyz]

upon the first boot up i checked Bios to see if everything is configured right.

All I did is OC the Ryzen 7 and set the XMP Profile for the RAM to 3600

 

[Dashhh]

Can you show me your voltage settings for the overclock, please? Set everything back to stock settings, disable your XMP profile, and reboot. Let me know what happens.

 

[Agoniyz]

How can I do that when I can't even get something on my screen haha.

 

[Agoniyz]

According to the MOBO manual, I can flash the bios via a button and USB stick with the latest Bios version. but it requires the CPU power cable to be connected...

 

[Dashhh]

Oh! Understood. I've been incorrectly under the assumption you can at least get to BIOS after misreading your comments. My apologies.

Get a new board and don't overclock this build until you have stable voltages, more PSU headroom (you have about 100 watts, but without knowing how hard you're pushing your system, you could have none), and more memory. I have to only assume the board is borked after implementing changes to the voltages. Not that you couldn't OC this build, but you're really pushing your limits doing so. In this case, I believe you did.

Cheers.

 

[Agoniyz]

Understood! Many thanks Have a great day!

 

[Dashhh]

You too! Keep me updated as you progress through this and I can try and help. The more information you provide up front, the easier it is for us to look into things for you!