Question Booted up PC. Suddenly turned off within 5 seconds. Won't turn back on but there's a green light on the mobo.

Jun 15, 2019
Booted up PC. Suddenly turned off within 5 seconds. Won't turn back on but there's a green light on the mobo.

So, the story.

Yesterday I went to pick up a prebuilt PC from someone. He had bought the pc I'm guessing 2-3 years ago. We booted up the pc at his house and everything worked perfectly. We brought it home and quickly downloaded Minecraft. As expected, we averaged around 400 fps. My brother played that until midnight when he went to bed. He accidentally left the PC on until about 4:30 in the morning. I went to get some water and noticed it was on so, I turned it off. At 7:30 I wake up and press power. Everything still works, the fans whir, the lights come on, but after 5 seconds everything turns off. I try to turn it back on but nothing happens. I take all the cables (keyboard, mouse, hdmi, ethernet) in and out then try to reboot it. Nothing happens apart from a small green light on the motherboard always comes on whenever I plug the power socket in.

Sorry for the long story, I have no idea where I mucked up.

I've tried to do that screw driver thing where you connect the power pins, doesn't work. I've also tried to switch the power and reset buttons with the pins, but that failed too. I've also tried holding the buttons down (whilst the pcs on and off) to no success. When I plug the power socket into the pc all that happens is a green light comes on on the mobo.

Not sur if this is important but it's collected a bucketload of dust. Like, loads. And I've got no experience in pc stuff.


Asus z170-p mobo
I7- 6700k
970 4GB
Corsair h60 hydro series high performance CPU cooler
Arctic mx-4 extreme thermal compound

Thanks in advance

Sorry if this is the wrong forum, I'm new.
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What you're describing is dead PSU and at worst case scenario, everything the PSU was connected to is also fried.

Corsair CS series, despite 80+ Gold efficiency, came only with 3 years of warranty (OEM: Great Wall). And Corsair PSUs are known to last just about the time given to them by warranty. Since you bought the PC used and it was in use for 2-3 years before, there's no telling what kind of abuse the PC and PSU saw at that time.

That being said, your 1st step would be getting new, good quality PSU. Here, i suggest getting any Seasonic unit, in 500W range. E.g: Focus 550, Focus+ 550, PRIME Snowsilent 550 or PRIME Ultra 550 Platinum

Warranty wise:
Focus: 7 years
Focus+: 10 years
PRIME: 12 years (includes all PRIME models: regular, Fanless, AirTouch, SnowSilent, Ultra)

(All my 3 PCs: Skylake, Haswell and AMD are also powered by Seasonic. Full specs with pics in my sig.)

Note: If given that your PSU fried something else when it died (PSUs can do that, especially low quality units, like yours), then new PSU doesn't fix the problem. Here, you need to replace all the components that got fried. MoBo is usually 1st to go when PSU goes sky high and so is GPU. So, once you got new PSU and still see no display on power on, rather than buying another new or used Z170 or Z270 chipset MoBo, i'd go with new CPU-MoBo combo. If the RAM survived then you can reuse it, if not, then get new RAM as well.
E.g this combo, pcpp:

Another option that you can do is to haul the PC to any local PC repair shop and ask them to check out all the components (e.g what survived and what didn't). It would cost you more to fix your PC this way but it would be faster time wise.

Btw, shorting the MoBo + and - power pins isn't something known by everyone, so you do have some knowledge about PCs and their inner workings.

Oh, life lesson as well: If you buy the PC used, always replace the old PSU with brand new one since it's really bad idea to buy used PSU, even when it comes in a working system. Also, if you clearly see the dust buildup in the PC, why on earth wouldn't you clean the dust from the PC?