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Desktop PC relucant to switch on!

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Community Gaffer
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Re: Desktop PC relucant to switch on!

This has happened to me on a few occassions where the monitor would never switch on. There are several reason this might be happening.. here is what I think could be happening.

I would check first for faulty memory. Take all of them out and reseat them into the slots. If still no dice, try just a single memory stick at a time (you may have just put the faulty one back in).

May even be worth reseating the graphics card too while you got the case open. Just lift out of slot and immediately put it back in.

If reseating and testing your memory & graphics card did not do the trick, try and get yourself a spare PSU from someone or buy yourself a new one. The former would be best as if it still doesn't work then you haven't wasted any money.

Last time this happened to me I found that it was the PSU in the end. But I have had brand new computers that would behave the same because of faulty memory.

The only other thing I can think of is to remove the graphics card and use the onboard graphics to see if your graphics card is faulty. That would be the last resort due to the price of new graphics cards.

Source: former certified IBM & HP laptop, desktop and server engineer for 5 years.

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Re: Desktop PC relucant to switch on!

@VileReynard - Note that just because you can’t hear any beep codes does not mean there are none as they system may not be in a position to generate them. Most MBs have a piezo electric sounder on them as connecting a coil speaker is so last century. I’d also have a look at the BIOS chip as well to see if it needs re-seating as I have seen these creep up  their socket due to vibrations and changes in temperature inside the case.

Another thing to look at are the fans. When you turn the power on do they all start to turn? If they don’t i.e. just pulse and stop then your PSU is looking like a suitable candidate for replacement. While on the subject you may also want to reduce the amount of power consumed at start up by eliminating as much as possible. As has been said the first thing I’d do here is disconnect all of the drives just to prove that the PC is actually booting.

You have said that you press and hold the power button to shut this down, now this implies to me that the system is up and running as if it were only at a bios screen it should shutdown instantly. Are you able to test with another monitor in case there is an issue with its backlight.

If you get very close to the monitor when you think the PC is (or should be) on see if you can see anything to indicate that the backlight has failed.

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Re: Desktop PC relucant to switch on!

Given the age of the pc, it is unlikely to be damage and more likely to be seating issues. As has been said, power off, remove the power cable (to stop it trying to power on), remove and re-seat the cards and memory. Remove power from all hdd & dvd's. Try to power up, if you get a bios screen then power off again and put the power back in the drives.

Vibration from the fans can cause the cards and memory to come loose a little and need reseated, more prominent in towers than desktops as there is no gravity issues on desktop bits helping the vibration.
VileReynard
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Re: Desktop PC relucant to switch on!

Very grateful to all responses - It's an intermittent fault in that it sometimes works first time - so could be hard to pin down.

I plan to pull the covers off tonight, maybe even measure a few voltages?

Will definitely remove any excessive dust with a hoover, totally ignoring the advice that says you must never do this. Grin

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Re: Desktop PC relucant to switch on!

I've had the faulty USB socket issue on a PC.

The PC would cycle through the Bios boot repeatedly and never get to the OS.

I disconnected everything from the motherboard not absolutely necessary and it booted.

I then started adding peripherals until it failed.

It was a front mounted USB socket which had developed a short and I replaced it.

The front mounted USB sockets often get a lot of use, more so than the rear ones.

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Community Gaffer
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Re: Desktop PC relucant to switch on!

@VileReynard, have you considered getting a PSU tester? I am starting to think that its your PSU that could be at fault after you said the issue is intermittent. It sounds like your PSU is slowly starting to die. It wont be long until it goes completely and you don't want it to take any components with it if it pops.

I have used one of these before:

http://amzn.eu/4vmMwAM

At the time, it let me know exactly what was failing on the power supply and so I invested in a brand new power supply anyway. It was just good to confirm that it was what I suspected before dropping a lot of cash on a new PSU.

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VileReynard
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Re: Desktop PC relucant to switch on!

I don't think I could cope with all those cables.

I suspect the last PSU I replaced was a 20 pin connector.

So I have just removed a couple of handfuls of dust from the PC.

The 24 pin connector has its connectors very close together and I can't see how to access the inside of the front panel.

I've taken a picture to highlight my problems...my-pc2.jpg

DS
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Re: Desktop PC relucant to switch on!

Fix

VileReynard wrote: (snipped)So I have just removed a couple of handfuls of dust from the PC.

 

Ok, so maybe you have shoved a fury animal through the rear vent!! Funny

 

With reference to the fan on top of the processor, it looks like you've missed a bit. Undecided The fan itself unscrews (4 in each corner), but don't remove the alli heat sink. An old tooth brush and a hoover normally does the trick. Wink

 

VileReynard
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Re: Desktop PC relucant to switch on!

Thanks - I didn't like to touch the fan in case I dislodged the heat sink.

I'm running the @Seti program and the CPU temperature is now a few degrees less - so I've reduced some of the fluff. Grin

The intermittent problem is still present though, so I suspect I'll eventually be forced to attend the corner shop to get it fixed. This would be the first time in 40+ years I'd have paid money for an IT fix, though. Angry

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Re: Desktop PC relucant to switch on!

It's very difficult to fix a fault that isn't there and impossible to be certain that you have succeeded.  So I wouldn't take your computer to the shop until such time as it fails to start frequently enough that you (and the shop) can be confident any supposed fix has actually worked.

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Re: Desktop PC relucant to switch on!

I don`t see any problem with "all those cables".... think of it this way... someone put them in... so you should be able to get them out.... they all have individual plugs... so highly unlikely that you will plug something in wrongly... and if you take them off one by one.... and do a couple of inserts/remove motions, that should clean the contacts, at least..

 

Logically thinking... if the PSU, is at fault... then it has to come out anyway.. if it is not at fault... then just cleaning up the plug-in connectors may solve the problem...

VileReynard
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Re: Desktop PC relucant to switch on!

Well, if the PSU has to come out, then I'll just have to grit my teeth and remove the cables.

I imagine the force on a 24 pin power plug is quite large.

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Re: Desktop PC relucant to switch on!

It is but I find the secret to getting them out is wrap your fingers round the cables, press the spigot with the thumb of the same hand and pull in the straightest line you can, it should be easy. But don't get too excited make sure the spigot is depressed or you could crack the board or damage the lanes.

wisty
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Re: Desktop PC relucant to switch on!

Most PC's have a power button & a reset button.

 

If you power it up, wait a second or two then press the reset button does it start?

If it does, that suggest the PSU is getting a bit tired, and taking slightly longer to build up it's voltages than the motherboard can cope with. Allowing the few seconds and then doing a reset allows the PSU to come up and then the Motherboard kicks in.

Powering it off and back on doesn't help unless you do it quickly enough that the PSU is still up when it all tries to start.

VileReynard
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Re: Desktop PC relucant to switch on!

There is no reset button.

But press & hold shuts the power off, whilst a short press starts up the PSU.

It's just that the start-up may require several start, press & hold cycles to switch on.

Once switched on I get no problems.

Therefore I cannot cycle the PSU on/off particularly rapidly.