Windows won't start

  David_LondonW 14:24 29 Feb 08

We have a HP Pavilion a640uk desktop PC, bought Dec 2004. We had serious problems with it about a month ago - thanks for helpful replies. The problem was basically triggered by a faulty keyboard making the PC go berserk. The keyboard has been replaced, and the PC is generally performing well. But we are still getting problems with Windows failing to start. Some days it starts first time, but on other days we get a sequence like: press power button; button lights up and fan starts; then nothing. Windows does not start; the start screen (blue on our PC) does not appear; there is a black screen without a cursor or any messages. Pressing F1 to get to the BIOS screen does not do anything. Sometimes Windows begins to start but reverts to the black screen without cursor.

We have checked the connections to the computer, also checked inside to ensure nothing has become loose.

Does anyone have any ideas? I wonder if it is the hard disk. I have looked at the Event Viewer and there aren't any errors reported. I will run CHKDSK but can't do it until I restart the PC which I don't want to do right now in case I can't start it again.

Once it starts the PC works really well. But getting it started is the problem.

Best wishes

  crosstrainer 14:28 29 Feb 08

This could be a symptom of a failing power supply or hard drive. Since the PC is "getting on" a bit, it might be an idea to open the case, and give it good clean...Power supplies collect dust in large quantities over time, and this can cause them to overheat and fail...Pay particular attention to the area around the fan(s)

  keef66 14:36 29 Feb 08

I'd bet it's a failing power supply. Seen those symptoms several times before.

Borrow one if you can to confirm this is the case.

Once confirmed, buy a decent one from somebody like E-buyer.
(or PC World if you can't wait, but check on their website first, and reserve it for collection in store; you could save quite a bit)

  David_LondonW 14:50 29 Feb 08

It's an ignorant question but is it a power supply problem if the power button lights up and the fan starts?

  crosstrainer 14:52 29 Feb 08

Yes it could still be the PSU, it's all down to the voltages it is (or isn't) supplying to the connected components in your system.....Light's and fan's do not constitute a guaranteed working PSU.

  keef66 16:13 29 Feb 08

Yes it can be; that's the thing that makes you think the psu is OK. In many cases they seem to deteriorate over time, at first only occasionally causing a problem, then becoming more erratic, before finally refusing to start the pc at all.

It would be the first thing I'd try anyway.

  David_LondonW 22:32 29 Feb 08

Thanks for your replies, looks like the PSU is the prime suspect. 2 more daft questions - how do I find out what PSU is suitable for this (other than emailing HP support), and how easy is it to install?

That said, if it is the PSU I wonder if it's only a matter of time before the hard disk fails as well, and it's worth a hard look at whether it would be more economical to replace the whole processor.


  Fruit Bat /\0/\ 23:28 29 Feb 08

If renewing a PSU check:

1. The physical size of your PSU, some are hard to replace due to being a non standard size.
2. The amount of power need from the PSU don't skimp.
3 The correct connections for your equipment

1. Physical Dimensions

Besides the specs and form factors, the physical dimensions are also important factors in selecting a compatible power supply. Here is an outline of the physical dimensions of most standard power supplies:

# ATX: 6x3.5x5.5", HxWxD. Most common. Uses 4 mounting screws.
# Mini-ATX: 5x3.5x5", HxWxD. Rare size. Uses 4 mounting screws. Can be used in a regular ATX case, but often not the other way around.
# MicroATX: 5x3x4", HxWxD. Use 3 mounting screws. Not interchangeable with ATX or miniATX.
# Flex ATX: Even smaller than Micro ATX. Various sizes according to case specs; often not interchangeable.

Use the data above to determine if a particular power supply would fit your case.

The quality of a power supply can be estimated by its weight. While this is not a true scientific or thorough measurement of the power supply reliability, it is nevertheless a very simple and easy way for ordinary PC users to estimate and compare the quality of a power supply.

2. Power supply calculator click here

3. Correct connections
Some boards have 20 pin connectors others 24 pin
There is often a 4 pin plug required to power Intel CPUs
Molex D plugs for IDE HDD and CD/DVD drives
SATA power connections for latest HDDs and DVD drives.

Guide to changing PSU
click here
click here

  keef66 17:41 01 Mar 08

if it is the psu and a standard ATX fits your pc, you should be able to get a decent branded 350W for less than £50, so you don't need to be thinking about a new pc (unless you're looking for an excuse to buy one!)

  skidzy 18:14 01 Mar 08

Most advise as i would normally to buy a branded psu of 400 watt or more,however i rebuild socket 478 and 775's and providing the computers is not used heavily for gaming,these are the psu's i use now click here basic but reliable,ive had no comebacks to date.

Just a small piece of advice that should suit you fine.

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