Question about HP Pavilion a305w (DM181AR) PC Desktop

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System fan computer not running , checked setup and reading that system fan not spinning (0 rpm) checked cup, and found no visual problems with any fans.

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Re: system fan

Lesbn man, if by your second post you mean the CPU fan is not spinning then that is likely the cause it won't boot. When the CPU overheats it'll start to do calculations wrong (causing a fault + restart or hang) or the BIOS will shut down the machine to avoid damage. Either one will keep you from getting into windows.

> Check for dust buildup on the CPU fan housing that could be keeping it from spinning. If clogged , blast it out with canned air.

> Check the power lead coming from the CPU fan to see if it connected to the motherboard.

> If you feel comfortable doing it you can further isolate the problem by plugging the CPU fan into one of the other 3 prong jacks that you have a WORKING system fan. If it spins up when you turn on the machine it's not the fan and you probably have a software config problem. Don't run it in this state for long (by that I mean seconds not minutes), you're just trying to see if the fan works at all. If it does it's likely what Nick described above.

Posted on Jan 26, 2008

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Re: system fan

You may have less fans than possible readings. That 0 rpm fan may be absent and so it is not the problem.

Posted on Jan 09, 2008

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New case fan running but still getting error message system fan failed.

Did you try;

Power off, power unplugged to computer.
Press the Power On button, and hold it in. Hold for a count of 10 seconds.
Let go.

Do this procedure two more times.

Plug the computer back into power. WAIT 1 minute, turn the computer on.

This method clears CMOS Error Codes, and sets BIOS Setup back to the factory default settings.

CPU fan spinning at required minimum RPM's?

Not talking about the SYS_FAN (Case fan)


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Unplug power and Open the computer case. Vacuum all the dust
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and Case...Make sure they are spinning easily and freely.
Plug the power in, and turn on your system. Watch the fans, especially
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You should try cleaning all the fans inside your PC once in a while.

Fans, especially in your video card would spin faster whenever you used the video card performance by playing online games that rely on graphics.

It is very normal. What is not is the annoying sounds you are hearing. It should not be. These sounds is cause by dirt accumulating on your blowers and fans. Just clean and the annoying sounds will go away.

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My monitor is not booting up but powered up, what is the problem? the fan is real loud but nothing else works

I see this is your second posting. Good for you in adding the additional information.
This may be rather lengthy genevacotton, so grab something to drink, and sit back.

The cooling system for a desktop computer consists of air flow through the computer case.
Air is brought in from the Front towards the Back of the computer. (Or for some gamer computers, through the top, or side, and out of the back)

Air helps to cool the hardware components inside the computer.
A Processor is one of the two main components to develop the most heat.

[ Below shows a typical Intel Pentium 4 processor. Operates at a maximum frequency rate, ('Speed') of 3.0GigaHertz,

Under the bold black heading > Intel Pentium 4 3.0GHz RK80546PG0801M ( BX80546PG3000E),
look at the tabs >
Specifications, Pictures (3), CPU ID, and Comments (0)

Click on > Pictures (5)

You can click on any of the photos to enlarge.

The photos show the top view of a Processor.
The silvery looking square case in the middle is the Processor chipset.
The Green square surrounding it is a circuit board.

Click on the third photo down. The one under 2008-10-05 14:56:45

Holding that circuit board up off of that flat black surface, are pins. These you do not see in the photo.
For this particular Intel Pentium 4, there are 478 pins.
This Processor fits in a Socket 478 processor socket.

The photo shows the top of the Processor's case, with No Heatsink sitting on it.

This is a typical Heatsink/Fan combo,

The Heatsink is the aluminum looking square object under the fan.
Your particular desktop computer may not use a fan on top of the Heatsink.

It may have a Fan in the front which draws air through a plastic tuned port.
The plastic tuned port in turn, then goes over the Heatsink sitting on top of the Processor.

Case in point with all of the above prattle?

The Thermal Paste used in-between the top of the Processor's case, and the bottom of the Heatsink, has dried up.

The top of a Processor's case, and the bottom of a Heatsink, are not perfectly smooth.
A microscopic view would reveal 'Pits, Hills, and Valleys'.
When the two surfaces of the Heatsink's bottom, and the Processor's top are put together, the before mentioned imperfections create Air Pockets.

AIR is an Insulator. Not a Conductor.
Thermal Paste is a Conductor. It conducts heat from the top of the Processor's case to the bottom of the Heatsink. and fills in the imperfections.

When thermal paste dries up it looses it's conducive properties.

The fans are designed to spin at an RPM, (Revolutions Per Minute), that is in compliance with the needed cooling for the Processor.
Processor isn't running very hard, fan/s spin at normal speed, (RPM)

Processor is running hard from multiple programs running, or intense games, the Processor heats up, and the fan/s spin faster.

Whenever the Processor heats up past it's thermal limit, (Maximum operating temperature), the fan/s spin faster.
If the Thermal Paste is dried up, the Heatsink, and Fan cannot cool the Processor properly.
The signal is given to the fan/s to speed up, but they still cannot cool the Processor.

The Processor overheats, and shuts off. The fans still spin at max RPM.
No computer operating, fan/s spinning at high RPM.

Nov 15, 2010 | PC Desktops

2 Answers

My computer makes a highish pitched whirring noise every time it has to do something slightly difficult, typically a video or interactive things. What is it and can I fix it?

Yes, open the side cover and determine where the noise is coming from - Harddrive, fans, DVD/CD player, etc.. If it's the harddrive, start backing up your important data asap before it goes out completely. If it's a fan, power down the computer and clean the fan. If it's t DVD/CD drive, replace the drive.

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1 Answer

The pc is switching on and then off after 5 minutes

There are several factors that could cause the above problem in your diagnoses.

A) Processor Fan is not operating, or not spinning at the set speed desired. (RPM. Revolutions Per Minute) Fan bearings are bad.
Replace processor fan.

Computer case open, observe the Processor fan as soon as you start the computer.
If the fan is not spinning, shut the computer down.
(Hold the Power On button in for a count of 10 seconds)

Observe if the fan spins slowly, or spins for a while, stops, then spins again.

B) Failing Electrolytic Capacitors on the motherboard.
C) Power Supply has a weak voltage power rail.

Failing Capacitors on the Motherboard.
Electrolytic Capacitors.
Specifically the one's used in the motherboard Voltage Regulator Circuit.

A Processor must have a Steady, Clean, supply of voltage.
The tolerance range is Very small.
Too little, or too much voltage, the Processor turns off.
[BIOS turns it off]

Part of what the motherboard voltage regulator circuit does, is to regulate voltage for the Processor.

This link gives information about what Electrolytic Capacitors look like installed on a motherboard, and photos plus info, about the visual signs of Electrolytic Capacitor failure,

(Computer unplugged from power. Observe Anti-Static Guidelines. Need more info about the last sentence, please post in a Comment)

Requires either replacing the failing capacitors, or replace the motherboard if bad capacitors are found.

If upon a close scrutiny with a flashlight, and magnifying glass, does not reveal visual signs of capacitor failure, then the next hardware component to check is the Power Supply.

3) Power Supply's have Electrolytic Capacitors also.
A computer power supply changes AC (Alternating Current) electricity from a household, or business, into DC electricity.
(Direct Current. A flashlight battery is an example of stored DC electricity)

Electrolytic Capacitors are used as Filters in a computer power supply.
They filter the incoming AC (Input Stage), and the outgoing DC (Output Stage)

Generally I have found that these are the weakest link, and are the first hardware component to fail in a PSU. (Power Supply Unit)

There is a way to test the Power Supply.
Requires either a multimeter, or a Power Supply Tester, or using a KNOWN to be good, compatible power supply to substitute, and use as a test unit.

An economical multimeter can be purchased for around $10 to $15 at many stores. An auto parts store usually carries them.
An economical power supply tester can be purchased for around $20.

This is an example of a power supply tester,

Computer dirty inside, as well as the inside of the Power Supply, will cause detrimental factors to the computer.

1) Dust is a Static magnet. Dust can create pathways for static electricity to follow, and the DC electricity used for a computer.
This can cause hardware components inside the computer to Short Circuit. (Fry out)

2) Dust, dirt, hair, etc, can clog the cooling components of the computer.
The computer case fan/s, the Processor fan, and Heatsink, and the Power Supply fan, and Heatsink/s located inside the Power Supply.

Air is drawn in through the front of a computer, (Or on some custom PC's through the side), and flows over the hardware components inside the computer, helping to cool them.

If a layer of dust, dirt, hair, and so on, has coated these hardware components, the heat will be trapped, and the air flow will not be able to carry the heat away.

If the computer case fan's are coated, their cooling capacity drops tremendously also. The fan, or fans, will not be able to provide the air flow needed.

If the Processor fan, and Heatsink are coated, the cooling capacity of these two components drops tremendously.
A Processor has a thermal temperature it can operate in, and will turn off if the temperature is exceeded.

It's a Fail Safe feature that is built-in, to keep the Processor from burning up.

[A Heatsink is essentially a plate of metal that has tall, thin fins protruding from it. Heat is absorbed into the plate, whereby it is then absorbed by the tall, thin fins.
Air flows in-between the fins, and helps carry the heat away.

This is an example of an average Fan/Heatsink combo,

The Heatsink is the aluminum finned part sitting under the fan.

Using a can of compressed air for computers, on a regular basis as needed, can help prevent many computer failures.

To summarize:

1) Check the Processor fan. If the computer is dirty inside, there is the obvious factor for it's failing.
2) Check the capacitors on the motherboard visually.
3) Test the power supply, or substitute it with a Known to be good, compatible unit for a test.

Must have at least the same amount of Wattage, or more.
Must have all the correct power cables needed.
Must have enough of the correct cables]

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1 Answer

Sytem fan is kaput

You geetin a false readin how can core 0 being a diffrent then core 1 when there the same waffer this is funny as all get out.. The ystem fan on this unit would be just below the power supply fan if you have one. If you do not have one then there will be little round holes there and you could look right into the case that means there is not fans present, Some manufactures do not power up the fan using the motherboard the piggy back it off one of the drive power cables thus you will get no reading at all Hence the sensor will not sense that there is a actual fan connected. If you where at 128 C you would burn the cpu you probably talking Fahrenheit? Anyway to remedy any situation you would need to buy a fan and put it where there is a place to put it in you case and plug it into the motherboard it should say FAN 1 etc etc.. Good luck

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Dell Dimension C521 power shuts off spontaneously

Procssor over heat can cause this kind of problem
check your processor cooler

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sounds like a fan is going out .. with the case open can you identify which fan is making the noise?

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