PC wont boot today

moid · 4 Jul 2009 at 23:14

PC has been working fine for the past 2 yrs, then suddenly this morning I get no picture on screen (fans all whirring etc just nothing appearing).

Try re-booting - same issue

Since then I have disconnected everything (other than CPU, mem and graphics) but still get the same issue.

I have tested both sticks of RAM and they work fine, I have also tried a different graphics card but this makes no difference.

The mobo makes no beeps at all (removed all RAM and this did cause beeps - so its not that the mobo beeps dont work).

I'm running out of ideas now. I'm left thinking its either PSU or mobo itself? Dont have a spar PSU to test, but power is getting to everything (all the fans are working etc)

Any suggestions??? :confused:

moppy89 · 4 Jul 2009 at 23:17

Maybe its your display? Or maybe the cable that connects to your display?

Those woulda bee nthe things I checked before dismantling my pc

moid · 4 Jul 2009 at 23:23

Sorry - should have said - I have already tested the cable and monitor with another system. No issues with these

Also tried resetting the CMOS

Minato · 4 Jul 2009 at 23:23

is your gfx overclocked? a cmos reset might help if so.

good luck mate, it can be frustrating, but it'll get solved sooner or later.

samuria · 4 Jul 2009 at 23:33

Do you get nothing on the screen or do you get the bios screen ok then nothing when it try to boot?

If you get the bios screen and as you say you have changed cmos I assume you have then the pc is all ok its a O/S issue what O/S?

Can you try a boot cd of any sort ie windows setup linux live cd?
Can you get in to safe mode?
Can you try another monitor its possible the monitor is being overclocked and shutting down

moid · 5 Jul 2009 at 00:20

I get nothing at all being displayed.

Just tested by PSU with the multimeter and I get 12V and 5V throughout so I dont think this is the issue either.

Getting a bit stumped now.

killari · 5 Jul 2009 at 00:32

Wow! an AGP graphics card!

I'm under the impression something has gone up with your motherboard. I once had an SLi motherboard where the primary slot would sometimes exhibit the problem you are facing now. Switching the slot sorted out my problem.

By the sound of it your PSU is ok. You can test the PSU by hot wiring it and if the fan spins then it works; even if the draw is too much for the psu your rig would atleast show the BIOS screen.

I guess its too much to ask if you have a spare mobo lying around?

moid · 5 Jul 2009 at 00:38

yes - I did the old paperclip and multimeter trick with the PSU - but thats seems fine and pushes 12 and 5V through the whole system.

Dont have a spare mobo unfortunately. Might have to pop the system into a local repair shop just to check I've not missed something daft! Any other tricks/tips before I take this step???

killari · 5 Jul 2009 at 01:10

Not that I can think of. If you are desperate you could always take everything apart, dust it out, reset all the cooling solutions with TIM, redoing the cabling and debugging from scratch.

The fact that you've reset the CMOS, tested a different GFX card and tested the monitor on a different system pretty much shows that its the mainboard with the problem.

I'm just gonna throw in some random stuff in the hopes that it may solve your problem:

Try the VGA port instead of the DVI

Take out the gfx card and use an airduster to clean out the apg slot, also give the connector on the card itself a good clean.

Turn off the pc at the wall and try again tomorrow morning (its amazing how this sometimes works).

Umm thats about it

Mattus · 5 Jul 2009 at 01:44

killari's ideas about cleaning it up and reseating everything are a good plan. It sounds like the motherboard may just be dead, though. I had a Gigabyte board that had the same symptoms - it would beep with no RAM installed, but otherwise it was dead. I just had to bin it in the end.

moid · 5 Jul 2009 at 01:54

cheers guys - will re-seat everything tomorrow but if thats no good then it may be a new purchase!

caithomas44 · 5 Jul 2009 at 14:02

Are you getting any beeps with the mobo at all? Or if you have an asus/austek are you getting any error messages on the lcd display on the mobo?

moid · 5 Jul 2009 at 22:15

No beeps. It is an Asus mobo but I dont have any lcd displays.

Tried setting everything - still nothing.

Must be the mobo

moid · 9 Jul 2009 at 23:29

---Update---

Got the new mobo (same version/model etc) and re-built the pc. Guess what - same issue still! Everything whirs/spins etc but nothing on screen. Suggests the mobo was fine after all. Doh!

I tried a different graphics card too. Although I don't get any image on screen I do now get a set of beeps (high low siren) when using this other card. I've read that the siren is often a sign that the it could be CPU related? Its the only thing left in the system that hasn't been tested and changed.

Any thoughts before I buy a new CPU too?

westom · 10 Jul 2009 at 16:02

moid said:
yes - I did the old paperclip and multimeter trick with the PSU - but thats seems fine and pushes 12 and 5V through the whole system.

That test said nothing useful.

First, what is voltage on purple wire when system is off (but connected to AC mains)?

Next, measure voltage on green and gray wires both before and as the power switch is pressed. Numbers must be to three significant digits and include behavior as that switch is pressed.

Whereas these numbers are probably constantly at zero, still, measure voltages on any one of orange, red, and yellow wires as the power switch is pressed.

Posting those numbers will then report definitive answers - no more doubts. And learn what those various wires do.

moid · 11 Jul 2009 at 10:03

westom said:
First, what is voltage on purple wire when system is off (but connected to AC mains)?

5.13

westom said:
Next, measure voltage on green and gray wires both before and as the power switch is pressed. Numbers must be to three significant digits and include behavior as that switch is pressed.

green - 4.90 before
gray - 0.00 before

green - used for paperclip i.e. cannot test this one?
gray - 0.05

westom said:
Whereas these numbers are probably constantly at zero, still, measure voltages on any one of orange, red, and yellow wires as the power switch is pressed.

all zero when pressed

numbers when on:
orange - 3.33
red - 5.04
yellow - 12.02
purple - 5.13
blue - -11.97
white - -4.91

From my untrained eye these look ok - anything I should be worried about?

moid · 11 Jul 2009 at 10:07

----ANOTHER UPDATE------

Got hold of another CPU (exactly the same one again). Guess what - thats right - still the same issue!!! Arggh!!!

When I use an old graphics card in the machone the mobo beeps at me (high-low siren). When I use my current GPU I get no beeps. But in both cases nothing appears on screen.

Unless the PSU test above comes back with an issue I have replaced every single item in the build but still no luck finding the cause!

Any further suggestions???

moid · 11 Jul 2009 at 10:48

ALL SORTED!!!!!

Turns out it was the bloody PSU afterall. Managed to borrow another one to test and hey presto - worked first time!

Oh well - off to the members market to put a Mobo and CPU up for sale!

Thanks for the help everyone

westom · 11 Jul 2009 at 14:46