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My computer doesn't start (no fan, no leds, ...).

I measure 12.74V on the 24ATX connector of the PSU. This falls outside the 5% tolerance. Can this result in the computer not starting anymore? Note: last week, we could still get it started by powering and unpowering the computer a number of times. I did a visual inspection of the capacitors but saw nothing unexepected.

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  • Marc Van Daele
    Marc Van Daele Dec 25, 2013

    I also tried replacing the CMOS battery and reset the CMOS but that didn't help either

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  • 22 Answers

Take it to a technical store or BestBuy. They should be able to help. Just take the main parts that you know that you need. One question though, did you have any modifications on that system?

Posted on Dec 25, 2013

Testimonial: "I did no modifications."

6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

sandrew
  • 2961 Answers

SOURCE: troubleshooting a computer that doesnt start

It's more than likely the CMOS battery a disk shaped 3V watch type battery found on the motherboard. Change this then reset time and other settings and your away.

Posted on Dec 26, 2006

SOURCE: Power up problem

One thing u can do also. Open your system case, remove cmos battery clean cmos battery and then insert like same. And restart your system. Other wise check power connections voltage. If it is ok then definitely it will wirk.

Posted on Sep 07, 2007

IB4G2008
  • 3587 Answers

SOURCE: pover up trouble

sounds like something is drawing down on your 12 volt supply drives or on board regulators. Try it without the drives connectged, and see if you can get the system to boot up(you'll just get a notice that your drives are unavailable, but you'll already know that, right?

got backup for your Dell?

Posted on Feb 15, 2008

Chuck68
  • 42 Answers

SOURCE: Front panel Ac Switch failing to start computer.

Try these steps.
If Power supply light does not turn on (or no power supply LED)
Perform the following steps, in order, until power is restored or it is determined that there is a hardware failure:
NOTE: If the Power Supply fan spins when the PC is turned on but the light does not come on, it is possible the LED is defective. If this is the case, use the section Power supply light comes on or flashes .
1. Disconnect everything from the PC, including the power cord.
2. With the power cord disconnected, press the power button on the front of the computer. Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
3. Replace the power cord with another power cord, like the one used by the monitor.
Test to see if the computer can turn on. If not, continue using these steps.
4. Ensure that the voltage selector switch is on the correct setting, 115V for North America.
5. With the power cord removed, flip the red voltage selector switch to the opposite position, wait about five seconds, and then switch the red voltage selector switch back to its original location.
This ensures that the voltage switch is engaged and set correctly for your country/region.
6. Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
7. Plug a lamp into the same outlet to see if the wall outlet has power. Try the computer in a different outlet in order to eliminate the outlet as a possible source of the issue. Test both to see if the wall outlets have power.
8. Remove all extension cords, power strips, surge protectors and any converters that remove ground. Plug the power cable directly to the wall outlet. Test for power. If this fixes the issue, find the device that is causing the issue and do not use it.
9. Use a vacuum cleaner to remove the build-up of dust from the power supply fan vent holes. Make sure that the PC is turned off and that the power cord is plugged into a grounded outlet. Only use the end of the vacuum hose near the outside of the fan entrance.
Plug in the power cord and test to see if the computer can turn on. If not, continue using these steps.
10. If all of the above steps have been tried and the power supply light remains off, use the steps in the next section, use the next section Power supply light comes on or flashes , to reseat the cables and check the power switch connector.

Posted on Jan 12, 2009

  • 1 Answer

SOURCE: Possible PSU problem?

i was useing my pc yesterday night and i woke up 2day to use and i had the same problem fan running without stopping and no blue light and nothing displyd on monitor. i opned it and i cleaned it with air pump and its working now. so try to cleane it with a good air pump. i hope mine stay working. good luck all

Posted on Mar 23, 2009

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I rebuilt computer with new parts, now won't start up. No POST. Power LED lights up, no cpu fans spin, no beeps. Psu works with paper clip test. New mobo, ram, psu, cpu.


Check display without cabinet maybe motherboard getting short with cabinet and try new Power supply check all the power supply connectors connected or not .

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The flickering green LED on the motherboard is illuminated by the standby power supply, a small completely independent, always on, 5 volt power supply labeled 5VSB usually, output is on the violet wire.

Here's some more detailed instructions about how to check a PSU.

Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

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The green light is blinking on the supply unit but it not coming on or booting up , i need to know if the supply unit is bad


Close examination of your power supply may reveal if the psu is bad.

When the power supply is plug in ac socket the green indicator led inside the motherboard will lit steady green. See if by turning on the cpu you will see some sparks in the power supply connector attached to the motherboard. This is a clear indication of a bad or shorted psu.

You can also smell if there is a burning inside the psu.

See if the fan inside the psu is working if not then its a clear indication of a bad psu.

Using a multimeter if you have one measure the dc voltage coming from the supply connector. Insert the black probe to one of the black wires in the connector. And the red probe to the red wire in the connector. the reading should be +12VDC. Put the red probe to the red wire and it should read +5VDC. Any readings below this, means bad psu.

Measure also the output voltage when there is a load in the power supply. Connect a CD-ROM drive or hardisk and measure again the voltage. Dropping of voltage when put some loads is a clear indication of a bad power supply unit (psu).

I hope this will help you.
Thank you for using Fixya!

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hello, I have a solution for u i think it may help for u.
your problem is:

When u press the start button... the power LED comes on but there is no POST beep or BIOS screen or boot up. The SMPS fan and Processor fans also dont come on at all. there is a small LED next to the SMPS plug on the motherboard that does light up when the system is connected to a power source.
Part of the system configuration is the kind of PSU you have in your system.
SOLUTION IS
So, what kind of PSU?

Try to borrow a known good PSU. Or better yet, see if you can test your PSU in another working system. If you cannot do that, try to borrow a DMM to measure the voltages. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

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FWIW Don't waste your money on another Bestec PSU

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for start

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