Pc Startup Problem

I have a computer which was running normally, including booting up and shutting down for several years until recently. The partial specs are:

Mid-Tower ATX Chassis w/300W PS P4PB400 Motherboard
Intel Pentium 4 Processor 2.40GHz with 512K Cache
512MB DDR333 PC2700 Non-ECC Memory (512MB x 1)
80GB IDE Ultra ATA 7200rpm Hard Drive
Windows XP Home OS


Sometimes my PC just seems to refuse to startup. When I push the power-on switch, I sometimes hear a short sound, not a beep, just distortion and then the system seems to come to a rest, nothing else happens. I cannot use a boottable diskette because it does not get that far.The light next to the power-on switch is green which means it supposedly getting power. My monitor stays dark, it is powered thru the PC. Once the PC is in this 'erroneous' situation, it shows no reaction at all to pressing the keyboard or moving the mouse. The fault seems to be getting worse since it originally started out as whine, whistle and some distortion when starting up.
I found out that in order to get the PC working normally again, I need to turn off the main power switch (located at the backside of the PC) and back on again, but most of the time this isn't successful the first time (I have to repeat this several times). When I finally get it to startup there is an high pitch sound like a whistle or whine and distortion. It stops when it finishes flashing the screen showing the Bios Version, then everything is normal

When I restart the computer by normal means (Menu -> Turnoff Computer -> Restart), the computer does restart but on restart there is an high pitch sound like a whistle and distortion before the welcome screen reappears then everything is normal

When I shutdown the computer by normal means (Menu -> Turnoff Computer -> Turnoff ), computer shuts down and I cannot restart the computer

Does this sound like the power supply is bad or going bad ?
Does this sound like a fan bad or going bad ?

Is there a software tool that checks for bad Power supply and fans etc ?

mike1628 said:

When I push the power-on switch, I sometimes hear a short sound, not a beep, just distortion

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Hmm, could it be an electicial crackle? If so it *could* indicate a loose wire/connection somewhere. Unusual sounds from a computer are usually a bad sign, you need to try to locate the exact source of the sound. Is it a very brief one or does it continue for a time?

mike1628 said:

My monitor stays dark, it is powered thru the PC.

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Does this mean that the screen is dark even though the power light is on? As the power for the monitor is coming from the computers PSU (a bad idea on principle in my opinion) then if the power supply was dead then the monitor would be completely dead, with not even the power led coming on. If however the led does come on but the screen stays dark then that's a different situation.

mike1628 said:

Once the PC is in this 'erroneous' situation, it shows no reaction at all to pressing the keyboard or moving the mouse.

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One thing I'm not clear on is if the monitor is still dead at this point. If so then the keyboard and mouse don't mean much and the problem is deeper than these.

mike1628 said:

The fault seems to be getting worse since it originally started out as whine, whistle and some distortion when starting up.

Click to expand...

Locate the exact source of the noise if possible. If the noises come from the fan then replace it immediately. A noisy fan is usually a dying one unless there's something touching it or stuck inside it.

mike1628 said:

I found out that in order to get the PC working normally again, I need to turn off the main power switch (located at the backside of the PC) and back on again, but most of the time this isn't successful the first time (I have to repeat this several times).

Click to expand...

It *might* be something as simple as a loose connection or a suspect power switch. Try unplugging the power switch from the motherboard and shorting the pins with a screwdriver (see this article), if the problem is simply a loose connection in the power switch then the computer should come on. Otherwise do a thorough visual check of all the cables, wires, cards, etc. inside the machine and make sure there are no loose parts.

mike1628 said:

When I finally get it to startup there is an high pitch sound like a whistle or whine and distortion.

Click to expand...

You need to somehow find exactly what is causing the noise, it could be the computers way of screaming in pain - listen to it and find out what it's trying to say!

mike1628 said:

Does this sound like the power supply is bad or going bad ?
Does this sound like a fan bad or going bad ?

Is there a software tool that checks for bad Power supply and fans etc ?

Click to expand...

A dying fan is the most likely possibility though not the only one. The best tool for debugging this at this stage are your eyes and ears!

Let me know how it goes and if you need any further help.

To me it sounds like a bad power supply of insufficient quality.

Im gonna side with Anti-Trend cause Im guessing you have at least one floppy drive and a cd rom of some sort and a hard drive, the mobo, and a processor that is 2.4 Ghz. I just don't think 300W would last very long. Since you said several years it has been running, Im already a little shocked. But back to the subject, I would try another outlet in the house that is on a different circuit. When I first moved in to my current house now, my computer was acting weird and the day I moved it into another room it runs smoothly. I came to find out my wireing on that circuit was screwed up.

yeah could be the power supply although i have a 300W power supply and it has lasted me 18 months, i have a dvd+/-RW and cd-rw plus various case fans and coolers, and lights, it has lasted great so far (touchwood, dont want to jinx it) although i am going to be getting a new one soon, a hiper 480W one, for future upgrades (not sli yet) but i think the power supply is the problem here, if its making weird sounds could it be sending the wrong voltages? because unusual sounds shouldn't be produced by normal voltages,

Hmm, could it be an electicial crackle? If so it *could* indicate a loose wire/connection somewhere. Unusual sounds from a computer are usually a bad sign, you need to try to locate the exact source of the sound. Is it a very brief one or does it continue for a time?.

Click to expand...

The noise that I had previously described is not coming from the case. The 'crackle' sound or whining noise comes from the speakers. Upon futher inspection of the wires connecting the speakers I found a loose connection and a bent prong in the connectors The power supply, fan etc is silent when I turn the machine on

Does this mean that the screen is dark even though the power light is on? ?.

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The light showing if there is power to the PSU is green (on).
The monitor is not dead The led is yellow but stays dark.

Locate the exact source of the noise if possible. If the noises come from the fan then replace it immediately. A noisy fan is usually a dying one unless

Click to expand...

It comes from the speaker

It *might* be something as simple as a loose connection or a suspect power switch. Try unplugging the power switch from the motherboard and shorting the pins with a screwdriver (see this article), if the problem is simply a loose connection in the power switch then the computer should come on. Otherwise do a thorough visual check of all the cables, wires, cards, etc. inside the machine and make sure there are no loose parts.

Click to expand...

I have not tried this yet but I do think it is either a dying PSU or loose connection as you have suggested.
Do you think I should get a new PSU either way ?

mike1628 said:

The noise that I had previously described is not coming from the case. The 'crackle' sound or whining noise comes from the speakers.

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Well done on finding that, that narrows the search down a bit.

mike1628 said:

I have not tried this yet but I do think it is either a dying PSU or loose connection as you have suggested.
Do you think I should get a new PSU either way ?

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I'm against the idea of spending money on parts on the chance that they *might* be needed. If you can, try and get a PSU from another computer and see if that makes a difference. On the other hand, getting yourself a decent PSU on general principles is a good idea. See the sticky Power Supplies and You for more details on this.