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Computer will not start


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#1 Matt Beaver

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Posted 29 March 2009 - 07:51 AM

Yesterday my brother (by accident, he says) unplugged my computer from the wall whilst it was still on. When he plugged it back in and tried to turn it on it failed to do anything. I got home that night and tried myself, also to no avail.

So, I've taken the computer almost completely apart to try and isolate the problem. I swapped the power supply to a spare I had and it still wouldn't turn on, I reset the CMOS, I checked the connection of the power button and that seemed to all be in tact and finally I even used a piece of wire to join the the positive and negative connections on the motherboard for the power button. Which all did nothing.

Please help!

My computer specs are:
Memory - 2GB DDR2
Processor - Core 2 Duo @ 2.2GHz
GFX Card - ATI Radeon HD 3850
Motherboard - Gigabyte GA-G31MX-S2
Storage - 120GB IDE

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#2 sparrow94

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Posted 29 March 2009 - 08:19 AM

i would have suggested the power-supply was bust. but if you are sure the spare was in good condition, then i couldn't be that

#3 garmanma

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Posted 29 March 2009 - 10:17 AM

As sparrow94 said, as long as you're sure the PS is OK, and you did those other tests, I'd say it's the CPU and/or the motherboard.
Double-check the the switch on the back of the PS wasn't inadvertently changed, the power cord is good and the power from the wall is OK

--------------------------------

Caution: There are electronics inside the case that are very susceptible to electrostatic discharges. To protect your computer, touch the metal of the case to discharge yourself of any electrostatic charges your body may have stored before touching any of the components inside. As a safety precaution you should unplug the computer to avoid electrical shock.
-----------------
The purpose of this procedure is to bypass the motherboard to test the PSU.

Caution:
This procedure will involve working with live 12VDC electrical potentials which if handled improperly may lead to electrical shock. Proper precautions should also be taken to prevent electrostatic discharges (ESDs) within the case of the computer. For safety purposes please follow the instructions step by step.

First, shutdown your computer. Then unplug the power cable going into your computer.

Once you have opened the case, touch the metal of the case to discharge any static electricity.

The connector of the PSU which connects to the motherboard is readily recognizable by the number of wires in the bundle. To disconnect it you will need to press on the plastic clip to disengage it and then pull the connector up and away from the motherboard. Please take notice of the location of the locking tab and the notch on the socket of the motherboard, this will only connect one way as it is keyed. This wire bundle will have a memory of the way it has been installed and will want to bend back that direction, you may have to play around with it to find a position that the connector will stay in the same position while you run the test.

Posted Image

From the top left to right the pins are 13-24, the bottom from left to right are 1-12.


Please notice that there are PSUs with 24 pin and 20 pin connectors, the location of the green wire in the 24 pin connector is #16, and the green wire in the 20 pin connector is #14. If you look at the connector with socket side facing you and the clip on the top the number one pin will be on the bottom left corner. This makes the pin out for the 24 pin connector from left to right 13-24 on top, and 1-12 on the bottom. The pin out for the 20 pin connector from left to right is 11-20 on top , and 1-10 on the bottom. If you look at the connectors you notice that these are sockets that fit over the pins on the motherboard where the PSU cable attaches, this is where you will place the jumper. For a jumper you will need a piece of solid wire about the size of a paper clip (20-22 awg), preferably a wire with insulation. It will need to be large enough to fit firmly into the socket so that it will not need to be held in place while testing. You are at risk of electrical shock if you are holding the jumper when you power up the PSU. Insert one end of the jumper into the socket of the Green wire, and insert the other end into the socket of any Black wire.

Once the jumper is in place plug the cord back in. If the PSU is working properly the case fans, optical drives, hdds, and LEDs should power up and remain on. I would suggest that you not leave this connected any longer than is necessary for safety purposes.

To reconnect the 20/4 pin connector unplug the power cord, remove the jumper, and reconnect the connector. Take a moment at this time to make sure that nothing has been dislodged inside the case.
---------------------------
At this point you can use a DC Voltage meter to read the different rail Voltages. You will want to insert the black probe into any of the Black (-) sockets, and insert the Red (+) probe in the five different colored sockets, one at a time. Below are the five different colors and their corresponding rail Voltages. The Voltages should be within about ten percent of the given values.

Yellow +12VDC

Blue -12VDC

Red +5VDC

White -5VDC

Orange +3.3VDC

Edited by garmanma, 29 March 2009 - 10:18 AM.

Mark
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why won't my laptop work?

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#4 Matt Beaver

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Posted 29 March 2009 - 10:54 AM

Ok, well, I think things may have just gotten more complicated.

I did the test you explained above with the PSU and it worked with the other power suply I have and not with my power suply already in the computer. But even when i connect the second power suply I have to my computer it STILL doesn't work.

#5 fairjoeblue

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Posted 29 March 2009 - 11:48 AM

Well "it doesn't work" is a pretty general description.

What does it do when you push the on button ?
Do you get anything on the monitor ?

What brand model is the computer ?

What brand of power supply is in it ?
OCZ StealthXstream 700W,Gigabyte GA-EP45-UD3R , E8500, Arctic Freezer Pro 7, 3GB G.Skill PC8500,Gigabyte Radeon HD 4850 OC [1GB ], Seagate 250GB SATA II X2 in RAID 0, Samsung SATA DVD burner.

#6 Matt Beaver

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Posted 01 April 2009 - 05:39 AM

When I press the power button nothing at all happens. Nothing shows up on the monitor, no fans start no lights come on, nothing.

The computer I built myself.

The power suplies I've tested it with are:
Silverstone SST-ST65ZF
FSP FSP300-60PNA(PF) (Power suply in the computer when it began failing to start up)
and ISO ISO-450PPP (Original power suply that came with my case)

#7 fairjoeblue

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Posted 01 April 2009 - 06:48 AM

If the computer was unplugged while it was on that shouldn't have cause complete failure.

If NOTHING happens when you push the on button disconnect the on button from the motherboard & touch a small straight blade screwdriver to the on button pins & see if it does anything.

If you jave a known good power supply & no fans , or anything else comes on, take the motherboard out of the case & see if it comes on.
If it doesn't the motherboard it totally dead.
OCZ StealthXstream 700W,Gigabyte GA-EP45-UD3R , E8500, Arctic Freezer Pro 7, 3GB G.Skill PC8500,Gigabyte Radeon HD 4850 OC [1GB ], Seagate 250GB SATA II X2 in RAID 0, Samsung SATA DVD burner.




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