[SOLVED] Long live the motherboard ?

[Yanitwei]

Dear all,

Recently my rig just died in midgame. It just shutoff and decided to long leave.
This is an old gaming build that I had for last ~10 years, never had any major issues and always maintained it well.

CPU: i7-6700K Overclocked to stable 4,2 GHz
RAM: A pair of Corsair Dominator Platinum 2666 MHz
Mobo: MSI Z170A Gaming M7
PSU: Corsair CX750M 80+ Bronze

What currently happens is that the motherboard does not POST, it does not start at all.
Though, there is a power in it, I can see the power button (integrated on motherboard) LED lights up when I plug the power cord, and when I press the button, FANs just wiggle for a second (they do not spin) and that's it, nothing else happens. Next time I need to unplug the power cable, re-plug it and back, press the button, and fans will wiggle again.

I've got a Debug Code LED (a pair of two 7-segments mini displays integrated on the motherboard), they do not show anything either.

As the first thing to go bad you may think of, I've connected a working PSU from a different PC (twice) and it's all the same result. Then, I worked my way by disconnecting every single connection from motherboard one by one and attempting to power on, trying to find a faulty unit or potential short circuit that prevents PC from starting.

Now I've reached to the point where literally everything was disconnected from motherboard (I mean EVERYTHING - all the FANs, SATA, NVMe, PCIe, USB and Audio jumpers, status LED and power on/reset button jumpers, even the CPU) leaving only 8 PIN CPU power connector and 24 PIN motherboard power connector. Well, it's all the same thing, no any signs of life.

Going further, I've attempted to update BIOS using FLASHBACK+ . It does not seem to flash the BIOS. Attempted to clear CMOS, same thing.

At this point I don't really know what else could be done, there are no capacitors on the motherboard to go bad, I have no idea how to get the south bridge radiator out (to check underneath) without breaking it, but to my finger touch it is solid cold.
I am pretty sure the issue is in the motherboard, but I don't think it is the BIOS chip, otherwise why would the motherboard simply shut down during everyday working process ?

I'm desperate for a help. I don't want to give up on this thing, yet. Any ideas will be appreciated how to further diagnose it to find the exact faulty thing and how to repair it ?

 

[Ralston18]

Will the system boot via Safe Mode?

How did you attempt to clear CMOS? Clear CMOS as instructed by the applicable Motherboard's User Guide/Manual.

Try a new, fresh, CMOS battery.

 

[SkyNetRising]

literally everything was disconnected from motherboard
(I mean EVERYTHING - all the FANs, SATA, NVMe, PCIe, USB and Audio jumpers, status LED and power on/reset button jumpers, even the CPU)
leaving only 8 PIN CPU power connector and 24 PIN motherboard power connector.
Well, it's all the same thing, no any signs of life.

Cpu, ram have to be installed. Without these it will not start.
Cpu cooler has to be installed too. Make sure cpu cooler fan is connected to cpu_fan header.
Also make sure to disconnect power from removed graphics card and sata drives.

If you removed cpu from socket, then carefully inspect cpu socket pins. It's very easy to bend/break them.
Make several high resolution photos of cpu socket from different angles and show here.

 

[Yanitwei]

Will the system boot via Safe Mode?

How did you attempt to clear CMOS? Clear CMOS as instructed by the applicable Motherboard's User Guide/Manual.

Try a new, fresh, CMOS battery.

No it doesn't boot anyhow. I've attempted to clear CMOS by jumping clear pins for 5 seconds, there's a corresponding LED that'll light if jumped. There's also a clear CMOS button directly on the I/O that does the same thing, so tried both ways, no results, I'll try to swap the batter in a minute.

 

[Misgar]

If your system is 10 years old and the CMOS battery is more than 5 years old, then as @Ralston18 says, the battery may well be the culprit. I've had several old systems which showed no signs of life, until I changed the CR2032.

After checking with a multimeter, my old batteries measured roughly 0.5V. A brand new battery should be circa 3.25V.

Although I have some working mobos dating back to 2006, it's possible your 10 year old CPU / mobo have succumbed to old age. In these cases, I search eBay for cheap "working" replacements and start swapping parts.

there are no capacitors on the motherboard to go bad,

I'd agree there are probably no electrolytic capacitors to go bad on your mobo, but you probably have solid dielectric equivalents, which are less likely to burst and leak brown goo.

 

[Eximo]

There are plenty of electrolytic capacitors in the pictures, just to be clear. None look exploded though.

The entire audio section has quite a few in yellow. There are several black aluminum electrolytic scattered around acting as local supplies. USB ports, some on the PCIe, probably as 3.3V buffers , and what appears to be a low voltage supply right in the middle of the board to the right of the CMOS battery.

Given the age, it is entirely possible your PSU has lost a voltage rail. Just seeing power on the board doesn't mean that 12V 5V and 3.3V are all working.

System could use a good dusting, I see quite a few bunnies sitting on the board. These can cause shorts if there is anything conductive in the dust.

It really is time to consider an upgrade anyway. This can easily be replaced motherboard/CPU with an i3-12100 with gains in performance, assuming the memory is still good. A new power supply should be purchased regardless of whether it is working or not. 10 years is a good run. If the PSU is newer than that, it is still not the highest end unit.

 

[Yanitwei]

Also make sure to disconnect power from removed graphics card and sata drives.

I can't believe I was missing this whole time! Turns out there was a short in one of graphics card power connectors.

I've pulled it out of PCIe slot but forgot to detach the 2x6 PIN power connectors. Then, when I brought a different PSU form working PC, I just hooked over 24 PIN motherboard and 8 PIN CPU power connectors, leaving everything else in place, that is what confused me, leading to think PSU/VGA are not the case and exclude them from the area of issue. Turns out the short circuit somehow was still in place.

Lastly, I got the motherboard out of the case, and before giving up for the day, decided to give it one last try. I brought third PSU, from my work PC, to be completely sure it is 200% working unit, on the table connected bare motherboard, CPU, one stick of RAM and PSU.
I pressed the button and it woke up! Rest assured! it was easy to find then what I was missing.

Now I'll think a bit on this GPU, I'll probably be opening a separate post in forum, but let's see how it goes.
Perhaps upgrading it is a good option, but I just don't like throwing things away just because they've stopped working.

Anyways, thanks y'all guys for prompt responses!

 

[SkyNetRising]

Now I'll think a bit on this GPU, I'll probably be opening a separate post in forum, but let's see how it goes.
Perhaps upgrading it is a good option, but I just don't like throwing things away just because they've stopped working.

I'd expect board level repairs to be required to revive the card.
Probably expensive.

GPU looks like Evga GTX 970. Not sure, if it's worth to send it in for repair.
RX 6500 XT would similar performance to your GTX 970.

 

[Yanitwei]

I'd expect board level repairs to be required to revive the card.
Probably expensive.

That is what keep things interesting, to me it feels like a lot less responsible job compared to motherboard repair, I can handle that.

Though, GPU is really old and not even supported anymore. I'll try to bring it back to life, and if I fail then I'll have a reason to buy a new GPU.

 

[SkyNetRising]

to me it feels like a lot less responsible job compared to motherboard repair, I can handle that.
I'll try to bring it back to life, and if I fail then I'll have a reason to buy a new GPU.

Not that easy. Not doable without specialized equipment and skills.
Watch some videos.

https://www.youtube.com/@northwestrepair/videos