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Desktop PC relucant to switch on!

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VileReynard
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Desktop PC relucant to switch on!

When I switch my PC on, more often than not, it does not fully power up.

The fans spin up, as do the disks and various LEDS (including the on/off switch).

However, the PC doesn't fully power up in that no video connection is made, nor is any boot attempt made.

The PSU is a CORSAIR 450W-450, the video card is only a 1GB NVIDIA GEFORCE GT730 and the CPU uses a bit more power - "AMD FX-4350 Quad Core CPU (4.3/4.2GHZ - 4MB CACHE/AM3+)"

The Motherboard is ASUSTeK model: M5A97 LE R2.0 v: Rev 1.xx Bios: American Megatrends v: 2501 date: 04/09/2014
But the question is:-

Is this caused by a PSU fault or a fault in the on/off switch?
Or possibly somewhere else?

BTW Trying multiple on/off cycles (up to 7 or Cool usually "cures" the problem.
This is a recent occurrence in a two year old PC.

72 REPLIES
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Re: Desktop PC relucant to switch on!

It could be something to do with the Linux Operating system......  

 

It does have some infallibilities from time to time...   Just like Windows  !

VileReynard
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Re: Desktop PC relucant to switch on!

So it seems I have a virus in my 'on' button? Funny

DS
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Re: Desktop PC relucant to switch on!

It could be OS related and I may be wrong, but It does sound like a PSU issue, possibly a capacitor has gone bad.

(also the rapid on off presses may give a bad cap chance to give the correct voltage to jump the boot section it has started to fail on)

If you know anything about the dangers/precautions with electrical/electronic/static then google is your friend (and it's quicker than me trying to type it all out and posting piccys up). It does give some good 'how to' write up's and videos when testing the output of a PSU used in a PC (some decent videos also include what voltage should be on what colour wire and you need to know the voltages before you even start)

Things like a multimeter would be needed.

 

Or possibly, as a simple let's rule this out is to buy a new PSU - possibly with a tad higher output, replace it (or have it swapped by another if you don't know what you're doing) and see if it boots correctly now, but check on the returns policy prior to purchasing, just in caseWink

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Re: Desktop PC relucant to switch on!

have you tried starting in the bios which would completely rule out the operating system

also try starting from a Linux boot disk

Browni
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Re: Desktop PC relucant to switch on!

I notice you said disks, try booting with only the o/s disk connected and powered.
I must have been really bad in a previous life as this was my 3rd ISP in a row that used lithium.
Now you're stuck with me because my new ISP doesn't run a forum Cheesy
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Re: Desktop PC relucant to switch on!


@VileReynard wrote:

So it seems I have a virus in my 'on' button? Funny


 

 

 

 

 

In your case.... most probably...... 

Community Veteran
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Re: Desktop PC relucant to switch on!

There is another possibility although I haven't seen it cause that specific problem

The on/off button is a press and release not hold on so try taking the front of the case off and press the button with the case not there and ensure it doesn't stick in

 

VileReynard
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Re: Desktop PC relucant to switch on!

After a failed start, following a press to "start", I'm switching the PC off by a push and hold - which switches the computer off via the BIOS. So I'm seriously thinking of replacing the PSU with an upgrade from 450W to 550W, using the same manufacturer so that I get a similar bundle of multi-coloured wires to deal with - thanks @DS

PeeGee
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Re: Desktop PC relucant to switch on!

You don't mention any "beep" code, so I would be tempted to remove and re-seat the memory first, then any cards.

It's unlikely to be a stuck switch as the power is staying on.

Phil

Edit2: I have run a similar system using an "EarthWatts" 350W - a power meter showing 85W idle and 150W peak.

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VileReynard
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Re: Desktop PC relucant to switch on!

OK - I suppose I should take the covers off before making any big investments!

DS
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Re: Desktop PC relucant to switch on!

No problem VileReynard Wink

If all of the suggested tests do not resolve this, then it does sound like the signal wire from the PSU to the motherboard has failed - it basically tells the motherboard that the PSU is healthy - from memory I think it's an orange wire. The HDD(s) will spin up in this condition as although they come from the same PSU, they're on a different internal circuit.

The computer will then just hang waiting for the healthy signal.

 

But to prevent any negative feelings, please don't quote me on this. Yours may not be the PSU and the last PSU repair I carried out was some years ago now.

 

Another common problem - the PSU fan was completely choked with animal fur - and no somebody didn't try to stuff a pet through the mesh!! Most of these were caused by laminate flooring and having the tower on the floor - carpets tend to catch the fur whereas it goes with the breeze on laminate.

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Re: Desktop PC relucant to switch on!


@VileReynard wrote:

When I switch my PC on, more often than not, it does not fully power up.

...

Is this caused by a PSU fault or a fault in the on/off switch?
Or possibly somewhere else?


Statistically, it's never the on/off switch.  This switch connects to a pair of pins on the motherboard.  Briefly short those pins together and the computer should turn on so you can bypass the switch if you want to be absolutely sure.

Although a bit of teasing was deserved, the problem is not your OS.

It can be hard to tell if a computer fails to boot or fails to provide an output to the monitor.  On a typical PC loading Windows, the Caps Lock light on the keyboard will go on and off and on again as the computer boots so that is one way of telling.

Assuming you are right and the problem is somewhere at the start of the process then the things you can potentially replace are the PSU and the RAM.  Remove and re-seat the RAM; if that does not work try one module at a time.

It could also be a peripheral or a USB connector with an internal short so disconnect everything you don't need.  Even the hard drive is not necessary for the computer to boot.  Look inside the USB connectors and check that you don't have any displaced, crossed wires.

If that fails and you have access to another PSU, try that.

If it's still not working then you are down to a problem with the processor or the motherboard.

 

 

 

SpendLessTime
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Re: Desktop PC relucant to switch on!

I have an old tower system where every year or so I have to reseat the video card as gravity moves it so slightly that it loses contact with its connectors. And refuses to boot at that point.

So it's case off, take all cards out, clean cards and inside case, check memory sticks are seated still, check all  cables and reinsert the video card. 

Works everytime.

maranello
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Re: Desktop PC relucant to switch on!

Waking up the monitor is more often than not one of the earlier stages of the BIOS, before checking memory, drives, etc.

Have you checked the video cables are fully connected. Disconnecting/connecting them would clean the contacts, and if you had a spare cable that would be worth trying.

Most BIOS systems have beep codes (a series of short/long beeps a bit like morse code), which indicates if a hardware issue is detected such as video card not connected to the motherboard. If you are not getting any beep codes or other indications from your BIOS then internal hardware issues are less likely to be the issue. The OS shouldn't have any impact on the video signal.

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