Dead PSU or Motherboard?

Triggaaar · 16 Dec 2013 at 12:34

I have a dead machine, but I'm not sure which piece is dead.

When I switch it on, the fans start to spin and the machine starts to power up. This lasts between 1 and 2 seconds, and then everything stops.

There are no beeps, it just stops with a little squeak (I'm guessing that's because the power has stopped, so things that were starting to spin up now start to slow down). I've opened up the PC, and looked for any diagnostic lights inside. With power from the wall on (not having pressed the on button), the only thing that lights up is the motherboard's Power button (as it should). When I switch the PC on, the only other light to come on is the DRAM LED. That LED goes off 1 or 2 seconds later when everything stops. The Power button remains lit, as it is still getting electricity.

Does this sound like a PSU failure, or a motherboard failure?

Thanks

ExRayTed · 16 Dec 2013 at 14:46

Sounds like power supply to me.

Disconnect everything bar a case fan (most power supplies need a load) and then test it

Triggaaar · 16 Dec 2013 at 15:23

ExRayTed said:
Sounds like power supply to me.

Disconnect everything bar a case fan (most power supplies need a load) and then test it

Thanks.

Are you suggesting using the paper clip, and a case fan?

Presumably a PSU that can power a case fan, and it's own fan, does not equal a fully working PSU?

ExRayTed · 16 Dec 2013 at 16:05

Agreed but it's a fairly good indicator

Triggaaar · 16 Dec 2013 at 16:08

Ok, unplugged the 20 (or 24) pin from the MB. Also unplugged some other bits, but I haven't unplugged everything yet, as there's so much plugged in to my PSU.

Used the paper clip and switched on, and almost nothing happened. I say almost, as I did see a case fan twitch. So a lot less happened than when I had everything plugged in, and it 'wered' for a second.

So maybe I haven't done the test properly, or I ave a dead PSU? The video did say the PSU fan would work 90% of the time, not all of the time.

ExRayTed · 16 Dec 2013 at 16:13

Dead PSU without a doubt.

Triggaaar · 16 Dec 2013 at 16:31

Plugged everything back in as it was, and now I get nothing (apart from the red light on the MB).

ExRayTed said:
Dead PSU without a doubt.

Ok, thanks. Will order the new one.

Triggaaar · 17 Dec 2013 at 18:38

Ordered after 4.30, and still arrived today. Very good, thanks OCUK.

Question:
My Graphics card needs two power cables: 6 pin and 8 pin. The new power supply comes with two main GC cables: both split into two, and each side has a choice of 6 pin or 8 pin. One says PCI Express, and the other says SLI ready. So...

Do I use one main cable, using 8 pins from (say) the PCI Express bit, and the 6 pins from the SLI Ready bit?
or
Do I use both main cables, using both PCI Express cables (since I'm not using SLI)?

I would guess that it's all the same, but perhaps it will take power from different rails? Thought I should check before using.

Thanks

OvEr_KiLL · 17 Dec 2013 at 18:43

what psu did you buy

just connect the 6 pin and the 6+2 (or 8 pin) from the same cable

Triggaaar · 17 Dec 2013 at 19:27

OvEr_KiLL said:
what psu did you buy

Super Flower, 650W. Do wish it was modular though, got cables coming out of my ears (which can't be right).

just connect the 6 pin and the 6+2 (or 8 pin) from the same cable

Thanks

Triggaaar · 18 Dec 2013 at 00:15

PSU replaced, system working.

OvEr_KiLL · 18 Dec 2013 at 00:20

Triggaaar said:
PSU replaced, system working.

nice one on the psu

yeh modular is way better for cable management

Triggaaar · 18 Dec 2013 at 00:44

OvEr_KiLL said:
nice one on the psu

I'd have gone for 750 or 800 W if I could. I hope 650 will be ok next time I upgrade the PC.

yeh modular is way better for cable management

On the plus side, my case is very cool with the new PSU. Can't shut the damn case!