PC Won't Power Up - Power Button Does Nothing? Need Help!

Gaarsin · Aug 6, 2016

Okay, I built my first PC about 3 weeks ago, everything went perfect, I haven't had any issues with the PC once it was set up, I've been playing games and doing work fine. Today I get back home and press my power button and to my surprise, nothing happens! The USB ports ARE supplying power as my keyboard & mouse LED's are lit up and the green motherboard light is ON.

What could have caused this? The PC has been working perfectly for 3 weeks and all of a sudden it won't power on? Nothing at ALL has changed. This is very annoying as I've spent over £1250 on this PC. Am I going to have to take it to a repair shop or is it possible this is a simple fix? I do not have access to spare parts to try out either if anyone was going to suggest so.

Please if you need anymore information to help, I will do my best to provide it ASAP and I would be very grateful if someone could help me out!

techgeek · Aug 6, 2016

When you say it doesn't power up, do you mean absolutely nothing happens? Like no LED's, not fans come on, etc?

If this is the case it is most likely the PSU. It is also possible that your case switch is bad. To eliminate the switch, you can short the two pins on the front panel connector header that the power switch is connected to. If it comes on, then it's the switch, if not then I would look at the PSU. If you have a motherboard with a power switch on it, then you can forego shorting the pins and just use that power button.

Also it might help us to help you if you give us a list of your computer parts.

Gaarsin · Aug 6, 2016

techgeek :

Yes, that is correct. No fans come on and neither do the LED's. Here is a list of my PC parts...

CPU: Intel Core i7-6700K 4.0GHz Quad-Core

GPU: NVIDIA GTX 1070 Founders Edition

PSU: EVGA SuperNOVA 750W G2, 80 PLUS Gold, Fully Modular PSU

MOBO: Asus Z170-A ATX LGA1151 Motherboard

HDD: Seagate Barracuda 1TB 3.5" 7200RPM

SSD: SAMSUNG 850 Evo 2.5" Internal SSD 250 GB

CASE: NZXT Phantom 630 Gunmetal Full Tower Case

RAM: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-3200 Memory

Gaarsin · Aug 6, 2016

techgeek :

I assume this MOBO has a power switch, I see a small black button with the labels PWR_LED & PWR_SW above it. Would it be helpful if I uploaded an image of the inside of my case?

techgeek · Aug 6, 2016

Ah yes, I've built three system using this motherboard. It's a pretty decent board.

So yes there is a PWR-SW located beside the COM port header at the bottom of the PCB. If you push this switch and your computer doesn't come on, then you need to have a look at your PSU.

Before trying another one, have a look and make sure that your ATX and CPU power connectors are fully inserted. It couldn't hurt to reseat them. If this doesn't fix anything, then it's time to try another PSU.

By the way that is a very good PSU, but there are always duds. We used to have a saying where I worked, "any tool made on a Monday or Friday is going to give you a problem".

Gaarsin · Aug 6, 2016

techgeek :

Okay, I tried pressing the switch and once again, nothing happened, the only signs of power are the LED's on my mouse, keyboard, and motherboard. What would you recommend now? Pulling all the PSU connectors from the back of the PSU and putting them back in? I'm pretty sure they're all in correctly and they don't seem to budge at all.

Thanks for the help so far, this is very frustrating. I just don't understand what could have happened? If this is a PSU issue what would be the reason for the PSU failing? Is there anything else I could try before trying a new PSU? I'm only asking because I need to order a new one, should I just return this PSU for a replacement? It has a 10-year warranty. Could it possibly be a faulty motherboard? I just find it strange that when I turned my PC off a few hours ago it was working perfectly, all temps very low, smooth as butter.

Also, I noticed a very quiet high frequency noise that seemed to dissipate when the motherboard PWR_SW was pressed. I assume this is normal and the reason I'd never heard it before was because of the fans moving.

techgeek · Aug 6, 2016

Well the first thing I would do is check the ATX and CPU / EPS connectors at both end. Sorry the first time I gave these instructions, I had forgotten that it was a modular PSU.

Usually when a motherboard fails, the fans and drives and other non-motherboard devices will come on. Since nothing seems to be getting power, I would say it's the power supply. If I were to guess it could be the inline fuse. Unfortunately it's not something you can change as it's likely soldered to the PCB. Beyond that, even if it is the fuse, there is no telling what caused it to fail to begin with.

Gaarsin · Aug 6, 2016

techgeek :

As far as I can tell they seem to be in perfectly, they aren't loose and won't budge at all. I tried pushing them in further but they seem to be in correctly. So, all I can do now is try a new PSU? I have an old PC with a really cheap PSU in it, would it be worth testing using this or wouldn't you recommend it? Also, will I need to ship the PSU cables back for a replacement? If so, this will cause lots of trouble as I've got tons of cable ties around them that would be difficult to remove without damaging the cables. Also, about that noise I mentioned in my earlier post, is that anything to be concerned with?

techgeek · Aug 6, 2016

Did you try reseating both ends of the cables? Particularly the ATX and power cable. One other thing I thought of, I have a SuperNova 1000 G2 and it came with an ATX block connector with a jumper wire. This is used to start the PSU with out motherboard connected to it. Did your PSU come with one of these? And if so, do you still have it? If so, unplug the ATX connector from the motherboard and plug it into the connector block I mentioned. Does the PSU come on?

As for testing with a cheap PSU, define cheap. How many watts is it rated for? You have a lot of expensive hardware that I'm not sure I'd chance to testing with a cheap PSU.

If you have to ship the PSU to EVGA, you'll have to ask them. In most cases they would have you keep the cables, but there is the possibility that it could be a cabling issue. If you have to send the cables back, I imagine they'd want the zip ties cut off of them. They are really easy to remove, just use a set of side cutters (wire cutters) and snip them off.

As far as the noise, without know the exact source I'd be hesitant to guess. It's unlikely the sound came from the motherboard. The most likely culprit would be the PSU itself.

Edit: Here is a link to a picture showing the connector block I was talking about. It's at the bottom on the left hand side:

Gaarsin · Aug 6, 2016

Yes, I've got one, it's the bottom left connector with a 4-pin Molex on one side (I think that's what it is anyway). The connector has DST printed on it, whatever that means. The connector above the packet of screws, right?

techgeek · Aug 6, 2016

I'm not sure how you are seeing the picture I linked to. The connector I am talking about is 24 pins (same as the ATX connector). Mine doesn't have anything printed on it. It has a little loop of wire on the back of it. In the image I linked, it's at the bottom next to the 4 little mounting screws.

Gaarsin · Aug 6, 2016

techgeek :

Nope, that connector isn't showing in the image you linked for me. The only 24 pin connector I have is the ATX motherboard connector. Would it be worth me purchasing one of these connectors you mention? Or would you recommend just returning the PSU, I just want to be 100% certain that it's the PSU that's at fault here before sending it back.

techgeek · Aug 6, 2016

I edited the picture and just cut and paste it to a separate picture:

You PSU should have come with one of these. I wouldn't bother ordering it if you didn't get one. It's more meant to power things outside a case without the need for a motherboard. They are great if you are bleeding a watercooling setup outside a case.

Gaarsin · Aug 6, 2016

techgeek :

Actually, I've got something similar to that, it's a little block inside a small plastic bag and has an EVGA Detection Tool sticker on the back, is that it? What do I do with this? Is it used for testing the PSU? I assume this is put into the ATX slot and if the LED's come on it's working? I'm probably completely wrong lol. The connector I'm looking at doesn't have a little wire connecting two pins together like the one in your image does, it also doesn't have the clips on the side.

techgeek · Aug 6, 2016

Yeah it has to have a jumper wire. It essentially shorts the PS_ON signal to ground which tells the PSU to power up. Essentially it does what the case power switch does.

Though not all PSUs come with these, the EVGA SuperNova series does. It should have been in the box. If you don't have it, then I guess the only other option is getting another supply.

There is a very remote chance something is wrong with the wall socket you are plugged into, or the AC cable to the PSU. You could try another cable and different socket. Though this is starting to stretch it. I think it's the PSU in my opinion.

techgeek · Aug 6, 2016

Can you take a photo of your "EVGA Detection Tool" and post it here?

Gaarsin · Aug 6, 2016

techgeek :

Check this image, I have the connector on the left, what is this used for? This isn't my image, I found it on another board: http://i.imgur.com/gJeJkk2.jpg

I've already tried another socket on the off chance that something was wrong with it but as expected, no change. I must have stupidly lost the jumper connector, such a fool. I can't remember having the connector at all though so maybe it wasn't packed in.

techgeek · Aug 6, 2016

That's it. They are both the same thing. I'm assuming the wire jumper is hidden in behind that cover. If it's got 24 sockets (only two will actually have contacts in them) then that's it.

It should only plug into the ATX connector one way. If you try this, first shut off the power switch at the back of the PSU. Then plug the EVGA Detection Tool (as yours is apparently called) and then turn the switch back on. If the PSU isn't dead, you should hear your drives power up (HDD spin up) if you have an optical drive, you should see the LED flash, that sort of thing. If nothing happens, then the PSU is dead.

Gaarsin · Aug 6, 2016

techgeek :

Just want to make sure before I do it. I need to pull the 24 pin power cable out of the motherboard and attach the EVGA Detection Tool to it and power on.. If the HDD and other components start working, does this mean my motherboard is dead? Thanks for helping me so much, I do appreciate it. I will try it right now once I have confirmation that this is correct.

techgeek · Aug 6, 2016

Yes, it's the 24 pin ATX connector on the motherboard. The EVGA Detection tool should be exactly the same length, and it will only plug in one way, you can't plug it in backwards.

If you hear your HDD spin up (presumably it's still connected to the PSU via the SATA power cable) or you see other indications that stuff is powering up (though obviously not the motherboard) then you know there is something not right with the motherboard. However I suspect that you will hear silence and it will be the PSU at fault.

Gaarsin · Aug 6, 2016

techgeek :

There isn't a slot for the two pins on the EVGA Detection Tool though, won't they bend if I put pressure on them? I've got it half on now but I'm afraid if I put any pressure on I'll end up damaging it.

Gaarsin · Aug 6, 2016

techgeek :

Okay, I connected it and powered it on and all the fans started spinning, the LED's lit up and as far as I could tell everything was working (although it's hard to listen to the HDD with all the fans going). Does this mean the issue isn't the PSU? I'm not 100% certain that the HDD was working as it's usually very quiet and the fan noise drowns out the sound but I'd bet good money that it was.

techgeek · Aug 6, 2016

Well if the fans are spinning then the PSU is able to turn on. That doesn't 100% mean that the PSU isn't at fault, though it is somewhat heading that way now. We can at least assume that the PS_ON wire and GND (ground) for turning the PSU on via the case switch are good.

Just to make sure, I think that you should power down your system, unplug it from the wall and start some major troubleshooting.

I would get the system as lean as possible to give it the best chance of POSTing. First, remove your graphics card. Disconnect all the SATA data cables. I assume you have two sticks of RAM, remove one. Disconnect your CPU / EPS connector and reconnect it. You've already removed the ATX power connector, so reconnect it. This is a barebones system. Now try and turn your computer on.

Let me know what happens.

Gaarsin · Aug 6, 2016

techgeek :

I've reconnected the motherboard power connector and disconnected the CPU connector and re-connected it. I'm not sure what EPS is? I also wanted to ask if I have to remove the GPU, could I not just unplug it from the PSU? If I have to remove it I will but I'd prefer not to. Also, does it matter what slot a single RAM stick is in? I know I had to use slots 2 & 4 when using two sticks.

techgeek · Aug 6, 2016

Sometime the CPU connector is labelled EPS that's why I used the slash.

As for the GPU, I said in my instructions to remove the graphics card. This also means you'll have to connect you monitor to the motherboard. Yes you need to remove it. Just disconnecting your PCI-E power cables from the graphics card will cause your system to not POST and that is what we are troubleshooting.

Your motherboard manual should tell you which slot to use for a single stick of RAM, but for troubleshooting I don't think it will matter.

PC Won't Power Up - Power Button Does Nothing? Need Help!

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