Question Computer Switches On then Off Repeatedly

Blindmonkey · May 29, 2019

Hi all,

I was wondering if anyone could help me.

I have been running a custom build desktop for around 3 years solidly, I use it roughly 4-5 hours a day and mainly for watching videos online, some light gaming here and there and at one point used it to edit a film, but that was a one off.

The machine has been running fine; however, a couple of days ago I turned on the machine and the desktop would turn on and then after around a second turn off. It would then by itself turn on again after a few seconds, only to turn off again once more, and so on.

The builds as follows:
CPU
Intel - Core i7-4790K 4 GHz Quad-Core Processor
CPU Cooler
CRYORIG - H7 49 CFM CPU Cooler
Motherboard
Asus - Z97-A ATX LGA1150 Motherboard
Memory
Kingston - HyperX Fury White 16 GB (2 x 8 GB) DDR3-1866 Memory
Storage
Western Digital - Caviar Blue 1 TB 3.5" 7200RPM Internal Hard Drive
Storage
Crucial - BX200 240 GB 2.5" Solid State Drive
Video Card
Gigabyte - GeForce GTX 960 4 GB Video Card
Case
Fractal Design - Define R4 ATX Mid Tower Case
Power
EVGA Supernova 550 W Gs Gold 80+ Modular Power Supply Unit

I have a ASUS VC239H 23 Inch Monitor, FHD (1920 x 1080), IPS, Frameless, Flicker Free, Low Blue Light, TUV Certified monitor and a standard USB mouse and USB keyboard, nothing fancy. Also I have a wifi USB receiver and a bluetooth receiver plugged via USB for a separate keyboard and mouse combo.

I have been in contact with EVGA, the PSU manufactures, and they have offered for me to send back the PSU to check the thing and if needs be repair it. I was just thinking I may be jumping the gun?

Checking online there are potentially many reasons, but in your collective experience would you suspect it is a PSU issue or is there usually another culprit? Additionally, is there any way to test which component it may be?

Thank you for taking the time to read this and in advance if you respond with advice

iiSlashr · May 29, 2019

Are you overclocking your CPU or RAM over spec? If so, that could be the source. Try resetting it to default settings via BIOS and opening the side of your case facing the CPU fan. It may be overheating or something similar.

CamperJoe18 · May 29, 2019

Does the screen go blank, or does the system completely shut down (no lights, fans off, etc.)? If it is a hard reboot, I would be quick to blame the PSU. Most of the other components in the system would at least give you a BSOD, but a hard reboot might mean a dead power supply.

If it does not turn all the way off (meaning you only loose the display, and not the entire system) I would re-seat everything (especially the video card and RAM) and check for broken pins on the CPU socket.

I feel your pain. I had to deal with a busted PSU a few months back on my primary system, and spent way too long trying to identify the issue. If you eventually reach a point where you just don't know what to do, I would either send the PSU in, or just buy a new one.

If you buy another one, and you figure out yours was dead, problem solved. If you buy another PSU and your system was fine, you just have an extra PSU lying around (which is not a bad thing, as power supply form factors are likely to remain the same for a few years/it gives you an extra troubleshooting tool).

CamperJoe18 · May 29, 2019

Also, you could try clearing the CMOS by unplugging your system and holding down the power button for 15-ish seconds. There might be a weird BIOS setting that is forcing a reboot before you load the operating system.

Blindmonkey · May 30, 2019

Thank you for getting back to me.

So, I got the thing back on by re-seating the RAM. So thank you very much for the suggestion.

However, there is now no display. I have tried two different monitors, both are working with other systems, and I have re-seated the Graphics Card, but it still nothing has shown up on the display. The system is back purring with all the fans on and the RAM and Power lights on solid.

So, at least I found out it is not the PSU, but I am guessing there is a bigger issue at play - does this topic need to be moved to 'displays' or 'motherboards'? Either way any help would be greatly appreciated!

CamperJoe18 · May 31, 2019

I would still try resetting the CMOS:

CamperJoe18 said:
try clearing the CMOS by unplugging your system and holding down the power button for 15-ish seconds

The next likely culprit would be any monitor cords, and then your graphics card. Try to switch out any cords you have (if you are using an HDMI, try diplay port; if you are using VGA, try HDMI; etc.), and then try to find another GPU that you might be able to switch out. That would at least help you identify the problem.

Blindmonkey · Jun 22, 2019

Thank you kindly @CamperJoe18 for taking the time to help with this issue.

I have subsequently sent the machine to a technician and he had a diagonsis that the motherboard had a failed component, but I moved the thread twice to here:

Question - Potential Issue Booting Due to RAM + Where to find cheap/test RAM?

Hi there, I have recently been posting on the PSU board regarding an issue I have been having with my build turning on and off repeatedly after powering on: https://forums.tomshardware.com/threads/computer-switches-on-then-off-repeatedly.3484496/ After initially re-seating the RAM the issue...

forums.tomshardware.com

then here: