Question about Dell Dimension E521 PC Desktop

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I have a Dell Dimension e521. My computer will not turn on at all. No power whatsoever. I took the side panels off and it was extremely dirty. A lesson is learned from this , I know. I am pretty sure there was minimal air circulation and no way for the hot air to escape. Is there anything I can do to get the thing going? My son really needs the machine. Thanks.

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  • Steve Oct 07, 2010

    Damn your'e good



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The two most common problems with a computer is,

A) It's dirty inside. (To include the Power Supply)
B) The Power Supply is bad.

As you suspected, the air flow removes excess heat from the hardware components, inside the computer.

1) If a Processor overheats it turns off. (BIOS turns it off actually)
This is a Fail Safe feature built-in.
A Processor could heat up so much that it would catch on fire.

The cooling components for the Processor, are the Heatsink which sits on top of it, and a fan.

Construction of a typical Heatsink is a plate of metal with tall, thin fins protruding from it.
The plate of metal absorbs heat from whatever object it is placed against, and the tall thin fins absorb heat from the plate.

The tall thin fins then radiate the heat away.
If a fan is used in conjunction with the Heatsink, the air flow helps to remove heat away from the fins.

Typical Heatsink/Fan combo:

The Dimension E521 does not have a dedicated Processor fan, that sits on top of the Processor.

The computer case fan in the front pushes air through a plastic tuned port, which in turn flows air over the Heatsink, sitting on top of the Processor.

2) Power Supply
The cooling components for the Power Supply are the internal fan, and Heatsinks used inside it.

This is an example of the internals of a typical SMPS.
Switched-Mode Power Supply, as used in today's personal desktop computers, and the Dimension E521,

View the photo to the upper right. You can left-click on it to enlarge.
(You can enlarge twice)
The aluminum rectangular finned objects to the right of the letter B, and to the right of the letter C, are Heatsinks.

Once the fan's blades, center hub, and surrounding cage, (Shroud), are clogged with Gunk, the cooling capacity of these hardware components drops tremendously.

The Power Supply overheats.
Heat = Wasted Energy
The Power Supply strains to keep up with the call for power, but eventually cannot, and components inside it fail.

This is where I believe you are at, diagnosis wise.
Bad Power Supply.

1) Buy a can of compressed air for computers. You may find you need more than one.

2) Obtain Q-tips.
I would suggest at least 30.
The Q-tips are just used to 'break the surface crust' of the gunk inside the computer, so the compressed air can remove it.
(Good for the fan blade to center hub area, and other places)

3) Observe Anti-Static Precautions, and clean the inside of the computer out.

4) Buy, and install a new Power Supply.

[Anti-Static Precautions:
Your body carries Static electricity.
Static will fry out (Short Circuit) the hardware components inside a computer.

You may not even see it, or feel it.

Computer on a table, computer unplugged from power, computer case open, TOUCH the metal frame of the open computer case.

While working on the computer touch the metal frame occasionally.
(Your hands will touch the case while working, but always helps to make sure)
Should you leave while working on the computer, be SURE to Touch the metal frame again upon your return.

The Dell Dimension E521 desktop computer, uses an ATX form factor Power Supply.

Dimensions of the power supply case are approximately,
6 inches Wide, 6 inches Long, and 3-1/2 inches Tall.

It is a 305 Watt rated power supply.
Know this; A computer only uses the power it needs, and NO more.
If you could install a 10,000 Watt power supply in that Dell, it would work fine.

Therefore if you find a good deal on a 400 Watt, 500 Watt, or 600 Watt power supply, go for it. (ATX)

However if you purchase a power supply for less than $30, you are taking chances. JMHO

Dell Support > Dimension E521 > Service Manual,

[ Removing and Installing Parts;

Opening the Computer Case; (Removing the computer cover)
Replacing a Power Supply; (Power Supply ]

Posted on Oct 06, 2010

Testimonial: "VERY very helpful info! I am running again and I learned a great deal on maintenance regarding heat related shutdowns. Thanks!!"

  • 2 more comments 
  • joecoolvette
    joecoolvette Oct 07, 2010

    I appreciate your rating, and kind words ssstevo2002!

    I also appreciate IceCake's solution, that added info about using the can of compressed air to clean the inside of the Power Supply out.

    Most useful, and information I forgot to add!

    [Power Supply unplugged from power, attach the plastic 'straw' to the nozzle of the can of compressed air. Suggest you start from the inside of the computer case, and insert the straw partially into the ventilation holes.

    Be sure to hold onto the straw with one hand, and use the other hand to hold onto the can of air. The straw tends to shoot off of the nozzle, and will wind up inside the Power Supply's case, otherwise.
    No fun trying to get it back out, lol!]

    Do Not attempt to open an SMPS!
    Inside are Electrolytic Capacitors. (Radial Aluminum Electrolytic Capacitor)
    Electrolytic Capacitors are designed to slowly build up a charge, then release it all at once.

    You may compare an Electrolytic Capacitor to a large swimming pool being filled up by a garden hose, then one wall of the swimming pool is taken down all at once.

    An Electrolytic Capacitor can hold a charge after being disconnected from electricity, for weeks, months, sometimes over a year.

    Should your finger/s touch the terminals on the bottom of a capacitor, the charge could be released to YOU!

    Should your finger/s touch a circuit that one, or more capacitors are in, your finger/s could complete the circuit, and the charge could be released to YOU!

    The shock can be Bad to Fatal.

  • joecoolvette
    joecoolvette Oct 07, 2010


  • IceCake
    IceCake Oct 07, 2010

    Thanks to you both. Glad I could be of some assistance. :)

  • joecoolvette
    joecoolvette Oct 07, 2010

    Glad you're here IceCake! We need more experts like yourself.


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  • Expert
  • 68 Answers

Buy a can, or two, of compressed air and blow out all vents, fan blades, anywhere that you see dust accumulation inside of the PC. When cleaning the fan blades, it's best that you just use an old toothbrush to remove the dust manually, because it tends to cling firmly on those particular parts.

Also, be sure to focus air around the vents of the power supply unit (PSU, power box). This is the box that powers your PC. Hopefully, this small task will be just the thing to breathe new air into your PC. :)

Hope this helps. :)

Posted on Oct 06, 2010

Testimonial: "Iam up and running again, great advise! It worked!"


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hi !
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Cheers !

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