PC Turned Off And Won't Turn On, Please Help!

Mechanicus

Mechanicus

Mechanicus

Associate
Joined
30 Oct 2007
Posts
161
Hello. I just received my graphics card, which was fixed, but now I have another, even bigger problem!

My PC was running fine for a few days, when some time on Wednesday it powered off for no reason. I tried to turn it back on but the power light only came on for a second (like when you unplug the PC and there is still a tiny bit of power still in the system). I pulled the tower out from under my desk and opened the side, but could not see any problem. I turned it off from the PSU and left it off for a while, in case there was an overheating problem, and after a while it turned on again first time. Thursday it worked fine all day.

But today I left the PC running while I did some DIY, only to come back and find it turned off. I tried to turn it back on but nothing happened, so I unplugged the power lead and left it for a while again (I don't think it could have overheated because it was still pulled out from Wednesday). I tried turning it back on after a while, and the case fans started up, as well as the hard drive, DVD drive and graphics card fans, but the CPU cooler didn't start up. I tried leaving it for a bit, but there were no progress/error beeps, and the computer didn't boot.
I couldn't turn it off by holding down the power button, and had to switch it off at the PSU. When I have tried turning it on since either nothing will happen, or the same as above.

I have tried a new power lead, and tried a different socket, but nothing changes. I also unplugged one the case fans and removed the repaired graphics card, in case there was a power issue, but that didn't change anything either.

Does anyone have any idea what could be at fault, and any ideas how I could further test to see what the problem is?

Sorry for any spelling/typing errors, I am using my mum's laptop and the keyboard is full of crumbs!
 
What is the full spec of the system and PSU make and model.

Were you overclocked at all, try a CMOS reset.
 
Sounds like the PSU is on its way out. What was wrong with the video card? Maybe the two are connected?
 
RJC said:
What is the full spec of the system and PSU make and model.

Were you overclocked at all, try a CMOS reset.
Click to expand...

Ok, this is off the top of my head, so some might be a bit wrong:

Windows 7 x64
Intel Core i5-2500K 3.30GHz
Asus P8P67 EVO
16GB (4x 4GB)
850W Corsair HX Series
Vantage A.L.C. CPU Cooler

No overclocking.

Sounds like the PSU is on its way out. What was wrong with the video card? Maybe the two are connected?
Click to expand...

There was a faulty fan on it, I think the bearings were going on it. OCUK sent it off to MSI for repair.
 
Is it possible to try any of the components in another system?

But do try the CMOS reset and try only one module.
 
Reset the cmos before trying anything else.

When I had this problem once it was the motherboard on its way out, then eventually died.
 
Bezzaboy1234 said:
I was having a similair problem with a almost identical system, the P8P67 board is abit dodgy in my opinion, I'd recommend getting a new Z77 board
Click to expand...


Well it's very generous of you to offer to buy me a new motherboard, do you want to paypal me the money?

I've had this PC for just over a year, and this weekend I was going to pay the last £100 I owe on it. There is no way I am buying new parts for a year-old PC. I hate being without a computer (It's been 2 hours and I already miss it), but the PSU has a 7-year warranty on it, the motherboard has 3 years, and even if it takes longer to get it checked and repaired/replaced, that's the only way I can do it.

Is it possible to try any of the components in another system?

But do try the CMOS reset and try only one module.
Click to expand...

No I don't have another system to try the parts on.
I am resetting the CMOS now. What do you mean only one module?

Edit:: CMOS reset did nothing, I also unplugged the DVD leads and all of the chassis fans. Only leads plugged into the PSU now are otherboard and 2x graphics card PCI-E leads.
 
Last edited:
Mechanicus said:
What do you mean only one module?
Click to expand...

Try booting with just 1 stick of ram, use the slot closest to the CPU.
Then if nothing try the other sticks 1 at a time. This will rule out the ram being the problem, or it will show that you have a faulty stick. I do however think it is a motherboard issue.
 
Ok, the PC is up and running again, and I think I know the problem, just not what end.

Basically I removed all the HD leads and the GFX leads, so the only leads left plugged in was the motherboard. I also removed all but one stick of RAM and tried turning it on. It worked!

So I slowly started putting RAM back until all 4 sticks were back in, then tried the HDs, then the graphics cards. Everything seemed to be working, so I finally plugged the chassis fans back in, and disaster! It wouldn't turn on!

So I removed the chassis fans, but still no luck, and I removed one of the graphics card, no luck again. I tried a third time, but while it was plugged in I knocked the motherboard lead slightly, and BAM, it started to work!

So it seems the culprit is the thick lead that plugs into the motherboard. The problem is, I don't know what end is the problem - the PSU end, or the mobo end.

Can you think of a way I can test it? I don't want my PC shutting down at random because of a faulty lead.
 
You can get PSU testers which plug in to the leads. You could also google ' paperclip trick psu' and then use a multimeter to test the voltages.

Try to verify (as well as you can) that the PSU works. If you have a multimeter, you can do a rough checkout of a PSU using the "paper clip trick". You plug the bare PSU into the wall. Insert a paper clip into the green wire pin and one of the black wire pins beside it. That's how the case power switch works. It applies a ground to the green wire. Turn on the PSU and the fan should spin up. If it doesn't, the PSU is dead. If you have a multimeter, you can check all the outputs. Yellow wires should be 12 volts, red 5 volts, orange 3.3 volts, blue wire -12 volts, purple wire is the 5 volt standby. The gray wire is really important. It sends a control signal called something like "PowerOK" from the PSU to the motherboard. It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. If you do not have this signal, your computer will not boot. The tolerances should be +/- 5%. If not, the PSU is bad.

Unfortunately (yes, there's a "gotcha" ), passing all the above does not mean that the PSU is good. It's not being tested under any kind of load. But if the fan doesn't turn on, the PSU is dead.

You do not need to remove the PSU from the case. You can just unplug all the PSU cables.
 
Last edited:
I think I would rather buy a PSU tester instead of electrocuting myself trying to stick paperclips in an electric current.

I got a little brave, and decided to wiggle the power supply, starting at the motherboard end and working down. No shut down.

So I don't know if it was a coincidence or what, maybe it wasn't the lead after all. It seems so random!
 
Last edited:
Looks the part.

Better delete the link though as they do compete on other hardware.

Voltage wise the max volts you will find outside the casing is 12Vdc or your mobo would really be in trouble.
 
Damn, I really have no idea what is causing this :(
I put it all back together, plugged everything back in and put it under my table again, no problems. I used it all yesterday, and left it on overnight, and then continued using it today.

But just now I was playing Minecraft, and the game crashed (dumped to desktop with no error message). This has happened before, so I wasn't that worried, but then about 10 seconds later my PC shut down.

I turned it back on straight away, and it came back on with no issues, my tabs on Firefox were even restored when I started it up again.

I use MSI Afterburner and RealTemp to check my CPU and GPU temperatures, and neither were even close to overheating, so I don't think it would have shut down for that.

I am worried it might have something to do with the repaired graphics card, because these problems only started happening after I installed it.
 
You must log in or register to reply here.
Back
Top Bottom