Computer fan prevent overheating

Dell computer turns on and off in a loop

Turned on your computer and it suddenly turns itself off then on in loop without successfully booting. Well you are not the first one to face this problem.  A lot of users experience similar problems with their dell computers and other systems including the examples listed below.

  • dell computer turns on and off in a loop
  • Turning on and 3 seconds later turns off.
  • Turning on but not displaying anything.
  • Computer shutdown while am still using it.

I have a curious mind so when something goes wrong i get excited at the prospect of discovering and learning new  things. This article will help you diagnose your computer that turns on and off. First lets look at the reasons why your computer is failing to successfully boot.

Main reasons why the computer turns on and off

  1. Overheating due to broken fan or malfunction of cooling system
  2. Power Supply Unit (PSU) malfunctioning
  3. Motherboard
  4. Hardware conflict and drivers issues
  5. Graphic card


Fan problems

From the computers i have had to fix that wouldn’t boot this was the most common cause. A friend brought a Dell Precision M4400 laptop which randomly turned off. On quick check we discovered that the fan was not functioning. if the laptop fan is not functioning well the computer automatically shuts down preventing internal damage from the heat. You can check if your Dell computer fan is working correctly using the Dell ePSA pre-boot system assessment.

  • Press the power button
  • F12 on Dell logo
  • Using keyboard select CPU fan

Just listening to the fan with your ears may sometimes not be the best idea since the fan stops when the system temperature is low.

With laptops since they are mostly placed everywhere on the bed, pillow which can block air flow and cause you computer to overheat and so on make sure the air vents are not covered to ensure a good supply of fresh airflow.

Dust build up causing heating

Computer systems depend on properly directed airflow to disperse heat efficiently hence dust build up interferes with the cooling system. This causes heating with time therefore you need to make sure that you dust your computer once in a while. Also the type of climate and environment you are in affects the rate of dust accumulating on your computer depending on the dust being blown to your computer.

On desktop computers its much easier to get rid of the dust, just open the casing and use a can of compressed air which you can get here to get rid of the dust . On the other hand opening laptops is a bit tricky. You will need to consult the manual or get technical help there if you haven’t opened one before.

Dirty motherboard and computer fan
Dust collecting on electrical components interferes with cooling system and can cause computer to turn on and off

Power Supply Unit (PSU) malfunctioning

Your dell computer will also turn on and off if the power supply unit is not working properly. For example, if the power supply unit is failing it your computer will start behaving weirdly sometimes not even powering up at all. Normally with modern PSU units even when they are not turned on they have 5-volt standby voltage which powers the computer components on standby. When you press the power button the power supply unit sends signal to the motherboard when the DC voltages are optimum and the computer can boot safely.

With the modern ATX power supply they have short circuit protection, temperature protection, power overload protection. So if it short circuits it will automatically power down automatically, as well as if it detects high temperature and so on. Electric shock when you touch the case of the computer may also be a sign that you have PSU issues.

If you suspect that the computer powers on and off because of the power supply unit you can easily replace or test it with a different power supply unit. Alternatively, you can use digital multimeters to measure the current whether it’s within the normal levels or not.

Warning power supply units can be very dangerous so when troubleshooting know what you are doing otherwise leave it to the technicians.

Hardware conflict and drivers issues

On desktop computers it’s easy to swap different peripherals even without much technical knowledge. This might however cause hardware conflict which will make the computer to suddenly shut down without warning or cause it to turn on and off attempting a successful boot. If you have installed new hardware you remove it and try to power on your computer without it. If your computer successfully boots, then you will need to figure why that component is conflicting with the rest of the hardware.

While conflicting hardware is no longer as common as it used to be its worth noting that it still occurs especially on legacy systems. Hence you can take out the different parts like ram and other PCI devices to see if it will stay on for longer. More like isolating the problem part.

On laptops you wouldn’t be swapping parts if you didn’t have the technical expertise unless of course you curious as I am and willing to experiment but I would strongly advise against it.

Also with Dell computers, you need to install the drivers in their proper order. If not correctly installed you will experience a of BSOD crashes.This article here covers how to  properly install dell drivers the correct way.

Graphic card and CPU Heat sink

As I have already mentioned above heat and computers are not friends. In actually fact you will see a considerable reduction in performance when your computer heats up. Had a challenge with the Dell XPS 15 which would suddenly shutdown without warning. It’s usually harder to diagnose a laptop like that as there seems to be not trigger to the problem it just happens randomly. I knew it was a heat problem cause playing games deceased the amount of time it was on. The solution was simple applying thermal paste. Over time the paste becomes so bad that it is not able to efficiently transfer heat to the heat sink. So again the computer will shut down from the heat.

An AMD Computer fan and heatsink
Heatsinks and computer fans reduce the amount heat on component like CPU and Graphic card

So if the fans are blaring at their maximum but your computer turns on and off check the thermal paste. If the paste is all dry and cracked replace it


A short circuit on the motherboard will surely cause your computer not to power up. While it will frustrate you it happens so no other components are damaged until you fix the root of the problem. A lot of computers will have their BIOS settings set to automatically attempt a reboot if it fails to boot. You can disable automatic reboot or just interrupt the boot attempt by pressing F2 or F12 if it’s a dell computer to select boot medium or enter boot settings.

If you have fiddled with the CMOS settings or they are corrupted, you might have triggered the repeated on and off. Consult your computer manually on how to reset the COMOS setting.


There is no one answer that will exactly fit you exact situation but using the above tests and tips you can be able to figure out what the problem is. Isolating the problem will involve removing some parts and encountering error codes and I find that an exciting learning experience. Let me know how you tackled your stubborn computer in the comments below.

One comment

  1. My older Optiplex GX270 has a similar – but different – problem. When it’s first plugged in to power, the computer cycles on and off every few seconds. Pressing the power button while it’s on (fan turning) causes it to boot normally. Shutting it down in Windows turns it off, and it doesn’t cycle. It can be restarted with the power button in this state. If it’s unplugged for a minute or so (wait until the yellow LED goes out on the MB), then plugged in, it starts cycling again. I’ve already replaced the MB because many of the capacitors visibly bad. Is there anything left to do except replace the power supply?

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