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Desktop Not Turning On . . . What do you think went wrong?

Last response: in Components
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December 7, 2010 11:14:38 PM

Condition of Desktop:
I was leaving the door open all the time. The fan would randomly become really loud. Not sure if this was CPU, Power Supply, or general tower fan that was really loud. It would also be really loud right before it went into sleep mode.

Last night i turned it off & now it won't power on. When the power cord is plugged into the power supply the power supply glows indicating power is going to the unit.

I believe the power supply died, but not sure. What do you guys think? Everything else was functioning perfectly right before I turned it off.

More about : desktop turning wrong

December 8, 2010 12:15:24 AM

It could be your power supply. Try checking your power supply's exhaust fan if it's turning when you're turning the PC on. Also check the cables if all are plug in. General tower fan would turn on at the moment you switch the PC power on cause if not then your PSU is busted.
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a b ) Power supply
December 8, 2010 1:41:12 AM

First, make sure all components of your PC are free from dust.
Second, re-attach all cables and make sure they're properly connected.
Third, If you are using UPS, try boot (turning ON PC) without using UPS.
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Best solution

a c 144 ) Power supply
December 8, 2010 8:41:04 PM

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the 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.

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.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
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December 10, 2010 2:25:02 AM

Best answer selected by ptsome110.
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December 10, 2010 2:25:49 AM

*

1. All Cables Plugged in Securely
2. PSU Fan does not Spin . . . Only PSU light turns on showing power is going to PSU (PC Doesn't Turn On)
3. UPS - I have no idea what this is. Based on google i think your referring to back up power supply if you lose electricity from the wall outlet. Then no i'm not using this.
4. There is some dust in the pc, but no more than was there when the pc was working the night before.


Thanks for all your help.

Using: http://www.tomshardware.com/forum/261145-31-perform-ste...

I should be able to find the problem.
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