Help! New computer won't boot :(

nicktay2605 · 27 May 2014 at 15:45

Hi guys, I'm having loads of problems with a new PC I built. Everything was working ok for a few months after build but then it wouldn't boot one day. I RMA'd the motherboard thinking that was the problem after performing the paperclip test on the PSU. However, they found nothing wrong with the mobo so I RMA'd the PSU and this was confirmed as faulty.

I've now received the new PSU and the PC still won't boot. I've taken the PSU and motherboard out of the case and tried connecting them together outside of the case. When I do this I get a green led on the motherboard light up, so it does seem to be getting power, but the CPU fan doesn't spin up. Could it be that the faulty PSU damaged the CPU? I can't see any evidence of damage on the CPU but I can't think what else would be causing it to fail to boot. I've also tried a different motherboard just to rule out the possibility that the motherboard is actually faulty.

Any ideas or suggestions would be greatly appreciated as I'm running out of patience with this now!

Nix · 27 May 2014 at 16:21

1. What wattage is your PSU?

2. Have you cabled correctly?

3. Is your PSU set to 220-230?

4. How far does your system boot? Do you get to POST, or does it not even start? Is your motherboard making any beeping noises?

5. Did the PSU work with the other mobo?

EDIT:

As another thought:

Have you tried replacing the cable and changing plug socket?

nicktay2605 · 27 May 2014 at 18:22

1. It's a Corsair CX430W PSU. The other parts in the PC are:

Intel Core i3 4330
4GB Corsair DDR3 1600MHz ram
Asus H81-M motherboard
64GB Kingston SSD
Arctic Cooling Freezer 13

2. Yes I've rechecked the cabling several times over and had the motherboard and PSU out of the case on their own

3. Sorry for being stupid, what do you mean set to 220-230?

4. The system doesn't start at all and there aren't any sort of beeps on the motherboard, just a green led that lights up

5. No, the same thing happened with the other motherboard. The other motherboard was brand new too, I bought it for another PC I was building at the time

6. Yeah I've tried it with two power cables and on a couple of different plug sockets.

Would a PC boot or show any activity at all if the cpu or ram were fried? I'm thinking that maybe the faulty PSU could have damaged some of the other components. Surely I can't have been sent another faulty PSU? This one has literally just come out of the box.

Danny75 · 27 May 2014 at 18:50

nicktay2605 said:
3. Sorry for being stupid, what do you mean set to 220-230?

I think Nix is referring to some PSU's that used to (some still might) come with a button to switch between 100V (approx) and 240V (approx). Correct me if I'm wrong.

Tested the Arctic CPU cooler on your other PC to make sure it still works?

Tested RAM in different slot?

neoglow · 27 May 2014 at 19:23

If it used to work but now dosen't I would be looking at the RAM and/or the RAM slots considering you got the PSU and mobo tested. Maybe a dodgy RAM stick or mobo slot.

Have you tried removing the mobo battery to clear the CMOS/Bios memory? You just need to pop it out its slot, wait a minute and then re insert it.

nicktay2605 · 27 May 2014 at 19:53

I haven't tried clearing the CMOS/Bios memory yet, I'll give that a go, thanks. Does anyone know if a PC would boot/show any signs of life with bad RAM installed or no RAM in there at all? I don't have any spare RAM to test unfortunately. Also, would a PC boot/show signs of life with a damaged CPU installed? I've swapped the Arctic CPU cooler for the stock cooler and neither seems to make a difference.

Nix · 27 May 2014 at 20:56

If it was bad RAM, I imagine you would be hearing some beeping.

To me, it sounds like it isn't POSTing at all. which says that either you're not passing the 'power-good' prior to POST or your CMOS is bust.

If it's not passing the 'power-good' it could be not enough power from the PSU, your CPU isn't asking for POST, or the motherboard has been damaged.

It's possible that a bad PSU has fried your CMOS battery which would stop a boot.

nicktay2605 · 27 May 2014 at 21:34

So I've just tried the PSU on another motherboard outside of the case (just the 8-pin and 24-pin connectors plugged into the motherboard and the CPU, CPU fan and RAM installed) and nothing. The PSU fan doesn't spin up, and neither does the CPU fan. Does this suggest that the replacement PSU they've sent me is DOA? Is the next step to take apart my main PC and try the PSU from that (which obviously I know 100% is functional) in both the motherboards?

Would a damaged CPU stop the PC from POST'ing? At this stage I can only think that it's a DOA PSU or the CPU was fried when the original PSU malfunctioned.

Nix · 27 May 2014 at 21:40

Yes it could.

Is your PSU fan spinning?

Have you tried plugging the PSU into other mains sockets?

Only way to rule out your PSU would be to try it on another system completely or get yourself an ATX PSU tester or multimeter tool and do it manually.

mightymouse · 27 May 2014 at 21:45

2 things from my own mistakes from past

1. do you have enough paste on it? I remember spreading mine too thin and it didnt post

2. check that you have damaged any cpu pins in the socket?

Good luck

PS PSU try to just use a paper clip to start it up? That way you will know for sure if it is the psu or mobo (only if you are sure but dont take my word for it)

nicktay2605 · 27 May 2014 at 21:56

The PSU fan isn't spinning, and yes I've tried it in different mains sockets, even in different rooms lol. I've heard that the paper clip test isn't overly reliable, I tried it on the faulty PSU I sent back and that PSU passed the test, but was still confirmed as faulty when it was RMA'd. Would a lack of paste stop the PSU fan and CPU fan from at least spinning? I'd have thought the PC would boot but quickly shut down due to overheating?

Would a faulty CPU have any noticeable signs of damage? It's impossible to test the CPU because I don't have another Haswell processor. I guess the next step is, like you say, to buy a PSU tester.

Nix · 27 May 2014 at 22:02

If the PSU's fan isn't spinning, I'd say it's DOA.

nicktay2605 · 27 May 2014 at 22:04

Argh, that's what I was afraid you'd say lol

Thanks for all the help Nix, I'll buy a multimeter or power supply tester so I can find out for sure and then look into RMA'ing it (again!)

Nix · 27 May 2014 at 22:06

Fans can be temperature controlled, but I'm not sure your one would do that, hence DOA.

If you do test manually, do some reading first. Don't hurt yourself.