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In the past month, for some unknown reason everything in my PC started to fail one by one. From CPU to hard disk. In the end of replacements and buying new ones, I have this:

  • MSI 970A-G46 (new)

  • AMD Fx4300 (new)

  • MSI AMD HD5770 graphics card (old)

  • Cooler Master 450w (replacement-new)

It has been around week or so since I assembled it all. Then this weird problem started to occur. After normal Shutdown(power supply on), I can't get it to start up. If I try within ten seconds, the power led starts blinking. And if I try after a few minutes, the light is on, the fans are running but nothing comes on the screen. Not even bios.

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    Sounds almost like inadequate CPU cooling to me, except for that inadequate cooling usually triggers hard shutdowns rather than making the system have trouble turning on. Did you properly apply new thermal grease to the CPU and install the heat sink and fan?
    – user
    Commented Aug 24, 2015 at 10:59
  • I did. And I have checked the temperatures, they're pretty normal. Around 67 ish .
    – Raghav Mahajan
    Commented Aug 24, 2015 at 16:02
  • There might be a problem with the machine's cooling, Machines do this when they overheat
    – kelvinelove
    Commented Jan 16, 2017 at 19:16

6 Answers 6

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Symptom: PSU rear switch cannot be re-powered within 1 min of previous shutdown. After power down, if the rear psu switch is turned off, the psu can not be restarted unless the rear psu switch remains off (or is unplugged) for 1 full minute.

The psu startup failure occurs every time and is caused by a flaw in the 5v OCP circuit, which prevents re-powering the psu within 1 minute of the previous shutdown.

Attempting to re-power the psu within 1 minute fails because the 5V line has not been discharged quickly enough, thereby triggering the OCP circuit.

The OCP flaw may be a design flaw, or an electrolytic capacitor has failed over time. Some motherboards have similar flaw.

The flaw may also be due to a short, an overloaded circuit, or a power brownout during time of day of peak power usage.

Solutions: -Move power cord to different circuit with less load. -Tidy up cable management to reduce risk of shorts -If a brownout occurs, PSU will shut down and needs to be reset by unplugging it or turning off rear PSU switch for 1 full minute. -Avoid turning off rear psu switch, and in situations where rear psu switch must be turned off, then leave rear psu switch off for 1 full minute before restarting. -Get new modular psu with new caps and new vendor. -Get new motherboard with new caps and new vendor.

=== :~) ===

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This kind of thing sounds like a voltage regulation problem and is a telltale sign of bad capacitors. Visually inspect all the capacitors on the motherboard and power supply (taking the PSU apart for this might void the warranty since it's new, so proceed with caution).

On the capacitors you will see a cross or K-shaped seam along the tops. The top should also be smooth and flat, with no bulge whatsoever. If you see a bulge (or if there is a rupture and you see electrolyte crusted on the them), then the capacitor is bad.

Capacitors

Since you said most of these components are new, they should still be under warranty.

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In my situation, the computer would not start after shut down. Every time I had to turn off the power with 0 button on the power supply. And you won't believe what was causing the problem. Display Port from graphics card. When I plugged in HDMI cable from the graphics card to monitor, all was working well. The issue never happened. Then I unplugged it, and I plugged in Display port cable from the graphic card to display port in the monitor, and baam. The issue happens again (after shut down it won't start).

Display port from graphics card GTX 1070to display port in the monitor was causing the problem. Why? I don't know. My guess is that display port cable tries to take more power from the power supply, and power supply tells, well you won't sir, and shuts down.

Ok, people, connect HDMI cable from your graphics card to HDMI in your monitor. Or if you don't have HDMI, try with a simple VGA port connection to VGA in a monitor.

Hope this will save some of you from headaches.

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My computer has this problem sometimes and it's related to a powered usb hub that I have to unplug. I guess it supplies power in addition to the power supply and therefore it doesn't fully reset unless all power is removed. It also may be related to the type of motherboard and the way it interfaces with my PCI USB expansion card.

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I'm experiencing the same problem with a brand new machine here. I'm using an Asrock B450M board with a AMD Ryzen 5 Pro 4650G.

What I tried

After starting up Windows, I did a regular shutdown. I waited a minute and pressed the power button to power up. The machine turns on, and the DVD drive lights up. No boot to Windows though.

Then I removed the power cable completely and reattached it. Windows boots normally. After shutdown, however, it didn't want to boot any longer.

I then tried another trick. I pressed the reset button (this machine has one) when the machine wouldn't boot. After that Windows would start normally.

My solution

I was pretty sure it wasn't any of the settings in the UEFI setup as I had quick-startup and deep sleep disabled. I also was 100% sure it wasn't the power outlet in the wall, because the same problem happened at a different home.

I ended up replacing the power supply with a different brand. That solved the issue.

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Over complicated answers to what is most likely a simple problem.

Go into BIOS and check for ErP which is a setting that dictates power to board in off state. Enable ErP and this problem should be fixed.

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