Question All of a sudden my PC won't POST despite no prior problems or hardware changes ?

[Kurohagane]

Hello, this is a bit puzzling to me, so if anyone can help me figure out what's wrong, I would appreciate it greatly.
So yesterday, I stayed up very late doing stuff and went to sleep at around 6AM after turning the PC off as usual. The PC exhibited no problems that I can think of at all in recent memory. I reluctantly woke up at 8:30PM after a nap for uni stuff, but when I tried to turn on the PC, the fans spun up, but nothing appeared on the screen.

System specs (GPU ~2 years old, rest is 1 year old):

CPU: Ryzen 5 3600X, stock cooler
GPU: XFX Rx580 8gb
Mobo: MSI B450 Tomahawk Max
RAM: G.Skill Ripjaws V, DDR4, 16 GB, 3600MHz, CL16 (2x8gb)
PSU: SilentiumPC Supremo M2 Gold 550W (SPC140)
System drive: ADATA XPG SX8200 PRO 256 GB M.2
Other drives: a two HDDs, and an unused sata SDD with (probably) a bad cable


Things I can tell:

• there is no signal to either monitor (one DisplayPort, one HDMI) from the GPU
• all of the fans are spinning except for the GPU fan (friend says it might just be because it doesn't spin at no load), GPU led is on as usual though
• the led labeled CPU on the motherboard is glowing red constantly, none of the other ones are on

Things I have tried without success:

• turning off the PSU and disconnecting it for a few mins then trying to turn on the PC again
• shorting the CMOS reset pins, and when that didn't do anything, taking out the CMOS battery for a few minutes

Things I was considering trying (tell me if these make sense or not):

• disconnecting all unnecessary peripherials and drives and trying again
• flashing an updated bios (as some people have similar problems with the tomahawk max, see below)

Anything even remotely relevant I can think of:

• a few months ago, right after cleaning/adding a new HDD/fiddling with drives, the PC would shut down a few seconds after powering on, but after a few times of doing that it fixed itself and it never happened again
• sometimes on startup the fans would spin up loudly to 100% for a few seconds, still not sure what was the cause of that but would happenin intermittently ever since the system was put together
• there is an unused SSD with what might be a bad SATA cable connected to the motherboard. Originally, I used it for my laptop, so it has a windows installation on it, but when I connected it it never showed up, so i left it like that out of laziness. Some time later when fiddling with the drives and reusing its cable for a new HDD, the new HDD did not show up either so I suspect the cable might be bad. Haven't gotten around to using a good cable for it yet, so it remains connected with the bad cable.
• I am faintly hoping that this is some software issue related to the mobo's software, as it seems some people have been having problems with the b450 Tomahawk max no-POST CPU led stuff for seemingly no reason

 

[TommyTwoTone66]

The things you are considering are sensible.

First, disconnect the "bad" SATA cable and "unused" SSD.

If that doesn't help, disconnect absolutely everything else other than the PSU, CPU, RAM and video card. You should at least be able to boot the PC into BIOS in that state and flash the BIOS (which is also a good idea).

If not, then something is wrong with the hardware. You would need to start swapping out components from a "known working" machine in order to figure out what is broken. With the fans spinning up and all the lights coming on it might be the CPU or RAM, but difficult to tell without swapping in known good components.

As an aside, it sounds like your "friend" has access to the PC while you are sleeping, is that correct? They may have sabotaged your PC so that you don't stay up until 6am hammering away on your keyboard. Don't discount this as a possibility.

 

[Kurohagane]

Thanks, I'll try those things when I have the time.

As an aside, it sounds like your "friend" has access to the PC while you are sleeping, is that correct? They may have sabotaged your PC so that you don't stay up until 6am hammering away on your keyboard. Don't discount this as a possibility.

Nah, maybe I made it sound that way, but it was just am observation from a friend over a discord call when I told him what happened. No one could have touched the PC, but now that I think about it, another thing that happened yesterday evening was one of the transformers blew up in the city and some parts lost power for a few hours (not mine, though). Not sure if that could affect the PC in any way, but at this point I am sort of grasping for straws, so might as well mention it just in case I suppose.

 

[TommyTwoTone66]

Yes, stuff like that can definitely affect your PC.

Everyone’s power is wired into the same grid. A lightning strike 100 miles away can shoot 1000V down your power lines for a split second which can wipe out electronics. A transformer blowing up and taking out half the city would definitely had some negative impact on your supply, whether the lights actually went out or not.

PCs are more vulnerable to power spikes than most consumer electronics such as TVs, Aircon units, fridges etc because those appliances have much higher tolerances and less complex power needs. The power supply in your PC is a delicate little flower by comparison and seemingly minor defects in the power to your home can destroy PSUs, motherboards and even CPUs in an instant.

At a minimum you should have your PC plugged in to a surge protector strip to somewhat protect it from the Wild West style power grid you guys seem to have over there. Ideally a UPS would smooth out even the strongest surges and brownouts.

From the other, previous stuff you were describing, I suspect that your motherboard was already flaky from the factory, and whatever happened last night has pushed it over the edge and finally killed it.

 

[Kurohagane]

That's interesting, and rather unfortunate if that turns out to be the case. Though, when this happened, the PC was on and was seemingly unaffected by the ordeal. Could it have had a delayed negative effect, or simply done something that would have only affected it after it was shut off 12 hours later?