Question No Display After Booting PC

[aaronlui100]

Parts List:

• CPU: Ryzen 5 7600
• Mobo: ASRock A620I Lightning
• RAM: 2x16GB Corsair Vengeance
• Storage: Crucial P3 Plus
• GPU: Asus TUF 3080 10G
• PSU: Corsair SF1000L
• Case: Fractal Terra

I went to boot up my PC this morning and saw that the fans were spinning, but my monitor didn't display any image. My PC had worked perfectly fine the day before, so I haven't changed anything since then to make it act differently.

After some testing on my own, I had some notes:

• Monitor works - connected to laptop with no issue
• Display cables work - tested multiple HDMI cables with laptop
• No display ports on GPU work (including reseating and making sure they are fully connected) - used cables known to work
  • Also no CPU display with motherboard - disconnected GPU and connected to motherboard display port
• PSU cables are fully seated - visual and physical inspection

That is the most I could think of to try and troubleshoot.

Here are some potential issues that could be the cause:

• Sometimes when I touch the case when the PC is on, it shocks me and causes itself to restart automatically
  • This could cause damage to some electrical circuits, but wouldn't explain how it turns back on every time without any issues
  • Edit: Probably due to static discharge, since other things like the metal part of a USB-C phone cable, monitor stand, and microwave also shock me occasionally. One thing to note is that all of these things are connected to a power outlet.
• Part of the GPU riser cable is touching the backplate of the GPU
  • I don't think this is a major problem, since it is only touching the outer corner of the backplate

After looking at some other forums, I saw that this is probably a component failure of some sort. However, I am not entirely certain which part would be broken in this case. If anyone has any idea what I can try, I would greatly appreciate it.

 

[Aeacus]

Also no CPU display with motherboard - disconnected GPU and connected to motherboard display port

This narrows things down to: CPU, MoBo and/or RAM.

So, one of those three, or all of them, are dead.

To validate which exactly, 2nd, compatible system is needed. Where you can test out all components individually. Don't put good, known to work hardware into your system, since system can kill those as well.

But without 2nd system, what little you can do, is taking out RAM and running 1 stick at a time. This may help. (Though, when one RAM DIMM would be dead, system would still boot up. But when both are dead, no boot up.)

Sometimes when I touch the case when the PC is on, it shocks me and causes itself to restart automatically

This is a BIG red flag.

You have good quality PSU (one of the best SFX PSUs actually) and PSU should never feed the live current to the PC case. So, there is some grounding issue. E.g screw under MoBo or MoBo standoff in the wrong place. Same with when power cable is smudged between panels and it gives live power feed to the PC case.

At this point, and to add to the 3 components above, i'd also include PSU as one of the problematic components.

Here, contact Corsair, explain the shocking issue in-depth and ask for PSU RMA.
I have never heard of Corsair SF-L to produce such shocking issue, but that doesn't rule it out completely. Either PSU has some serious internal fault (sending live voltage to ground, thus energizing entire PC case), or you have some power cable pinched somewhere, with isolation gone and making connection to the PC case. After all, your system is small mini-ITX and cable pinching is easy to achieve in cramped spaces.

 

[aaronlui100]

You have good quality PSU (one of the best SFX PSUs actually) and PSU should never feed the live current to the PC case. So, there is some grounding issue. E.g screw under MoBo or MoBo standoff in the wrong place. Same with when power cable is smudged between panels and it gives live power feed to the PC case.

Thank you for the feedback. I think some important context that I should have added is that since it is winter time, static electricity can build up more. Therefore, it could be possible that static is damaging the PC, since it is not just the case that occasionally shocks me, but anything metal (e.g. USB-C charging cable, monitor stand, microwave). I'll update the original post to include this detail.

I read somewhere that when the PSU encounters sudden high voltage, it automatically shuts itself to prevent damage to itself and other components. However, given that it has always rebooted immediately following a shock, I am not certain as to why it is just not showing any image anymore.

Thanks again for the help, I will be contacting Corsair to see if they have any solutions.

 

[Carman235]

I am having similar issue, but I was compressing hard drive with os on it, restarted when done, got in the windows, but not one program started.. I restarted it again, and voila, no signal to the monitor, one beep and that's it.

First I thought it's the hard drive, so I changed it with a fresh empty one, got USB with windows on it, but the issue is still there, no signal, can't boot, nothing..

Now I am suspecting that static had something to do with it.. It could be, that my cat rubbed against it, I have one side open because radiator doesn't fit in all the way, and that way some static would jump to computer..

 

[Aeacus]

I read somewhere that when the PSU encounters sudden high voltage, it automatically shuts itself to prevent damage to itself and other components.

That's SCP (short circuit protection) and would kick in once PSU detects impedance of less than 0.1 Ohms in output rails, thus shutting PSU off.
Further reading: https://www.tomshardware.com/reviews/power-supplies-101,4193-21.html

But SCP is to do with output rails PSU is outputting. ESD (e.g you touching PC's metal casing) would make the voltage charge to travel to the PSU's metal casing and directly to the ground wire, via main power connector, without triggering SCP.

All other PSU protections, like OCP, OVP, are all also to do with what PSU is outputting via it's rails, and not what is "fed back" to the PSU.

For PC case to be energized and PSU triggering the shut down due to SCP, once you touch the PC, there has to be direct connection of one of the PSU rails into the metal casing of the PC.

 

[COLGeek]

One thing to note is that all of these things are connected to a power outlet.

Is everything connected to the same outlet?

Static can do odd things. Just today, I touched by mouse, received a shock, and it caused one of my two displays to "restart". Nothing else seemed to be affected.

Can you change to a different outlet (hopefully on a different electrical circuit/breaker) to see if that changes behavior?

 

[Eximo]

I'm not really sure there is a distinction between input and output when it comes to over voltage protection. Current flow is one thing, but if you put a huge potential on a circuit, the current at that voltage it is going to flow to a point of lesser potential, so it would show as a negative voltage to the PSU side of things, I think. It may even convince the PSU that no voltage is going out for a brief instance.

I would have to sit down and simulate that with P-spice or something.

Electronics generally have POST circuits that latch, if you interrupt that latch with a brief shock, again I could see that causing something like a monitor to flicker off briefly, but the capacitors are still charged enough to recover quickly.

You can also check that your outlet itself is actually grounded with an outlet tester. They go for around $5-8 for the non GFCI ones.

---

More on topic, I would disassemble the system and take it back to basics. Any component could have failed, regardless of the source of the damage. I would test the powersupply in isolation by grounding the standby pin to one of the ground pins (paper clip test) If you have a multimeter you can check the open circuit voltage.

CPU, Motherboard, Powersupply, and a single stick of ram (swap sticks and slots as well). Heatsink fan can even be unplugged. Test just long enough to confirm if it works or not.

If it boots up, shut it down and start plugging things back in one at a time until it doesn't. Then you have found the problem, or the system is rebuilt and working, original issue unknown.

Bad cables, bad drives, bad PSU, bad fan, you name it. If it is shorted out it will prevent POST on the PSU or system. (I had a system get as far as Windows starting to load, turned out to be a bad PSU SATA power cable that provided power to some of the front I/O.

If the CPU or motherboard has failed, more difficult to test without other hardware. But you can at least narrow it down.

 

[aaronlui100]

For PC case to be energized and PSU triggering the shut down due to SCP, once you touch the PC, there has to be direct connection of one of the PSU rails into the metal casing of the PC.

Could dust or bending of PSU cables be a potential cause of this? Without a dust cover on the Fractal Terra, there is a higher amount of dust entering the PSU than usual. However, the system is only 2 months old, so I doubt there would be enough to make a difference. As for the cables, the SFX-L form factor makes the available space for cable routing very tight, causing tight cable bends that just barely fit into the case. With everything so close together, maybe something is going on, though I also doubt this to be the cause.

Is everything connected to the same outlet?

No, however they are likely on the same circuit. Given that my uni dorm is fairly old, there is a realistic chance that the grounding is faulty. I'll still try plugging it into a separate circuit, though.

More on topic, I would disassemble the system and take it back to basics. Any component could have failed, regardless of the source of the damage.

Unfortunately, my PC is currently the only source of hardware that are compatible with the components in my system, as I am at college and PC components are hard to come by here. Still, I appreciate the response and will do that as soon as I get the chance to.

 

[COLGeek]

I highly recommend you never use the microwave while using the PC if on the same circuit. One or the other, but not both.

 

[Aeacus]

Could dust or bending of PSU cables be a potential cause of this?

Dust, no.

Dust isn't electrically conductive but it does act as heat shield (preventing proper cooling for the system). For dust to be problematic, your system should be filled with dust. E.g 5+ years without internal cleaning or 1-2 months in VERY dusty environment (e.g in industrial setting that produces a lot of fine particles, like sawmill or sugar mill).
Dormitory doesn't have such high levels of dust (usually), to make your system to collect excess amounts of dust.

That is, unless you have high humidity in your room. Then dust can get wet and become partial conductor.

PSU cables are insulated and while bending power cables hard/sharp isn't ideal, all is good until power cable isn't pinched so hard, that damage goes through the insulating, reaching bare wire inside the power cable.

Another possible option is that when there's connection between unused power cable connector (e.g SATA or MOLEX) and PC case. E.g you have unused connector inside the PC case, but some parts of the PC case is actually poking into said unused connector, thus bridging the cap and making a connection (in lieu of you sticking small screwdriver into SATA/MOLEX connector to make a connection).

Given that my uni dorm is fairly old, there is a realistic chance that the grounding is faulty. I'll still try plugging it into a separate circuit, though.

Once you get your PC issue sorted, moving forwards, good quality UPS would protect against main power grid issues. Namely line-interactive topology, true/pure sine wave UPS. And preferably same wattage capacity as PSU is.

Unfortunately, my PC is currently the only source of hardware that are compatible with the components in my system, as I am at college and PC components are hard to come by here.

In this case, i suggest you haul your system to PC repair shop and pay for diagnostics. They have proper hardware (2nd, compatible system) to tell you exactly which components died. Diagnostics doesn't cost much money. PC repair shop can also quote you the price for component replacements (aka fixing your PC wholly).

For uni/college, i'd suggest using laptop instead, rather than desktop. Laptop is more portable and cheaper to replace, if something should happen.