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The " oh ****, please help me" thread.

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June 26, 2011 1:58:08 AM

Hello Tom's Hardware,

I have a four-year old HP computer (model #a6402f) at home that won't boot at all. Before this problem occured you could go on it for about 10 minutes before it goes to the blue screen. I can still hear the fan and the tower running but the monitor says that it is receiving no signal at all. You could still run it but now it got worse as just goes straight to the black screen as I have said before. Also, I built my own computer and connected it to the internet a few hours ago before the problem occured. I suspect it may be a problem with the computer's motherboard or ram as I've seen around the forums with people facing similar problems. The HP computer contains alot useful information that cannot be lost.

What do you suspect it could be the problem. Is their a way to fix it at home or do we need to take it for repairs?

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June 26, 2011 2:12:45 AM

It shouldn't be the HDD, so your data shouldn't be lost. If you really need it now, hook it up to another computer and copy it out.

It could be a PSU problem, try booting with alternate RAM?
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June 26, 2011 3:02:48 AM

Timop said:
It shouldn't be the HDD, so your data shouldn't be lost. If you really need it now, hook it up to another computer and copy it out.

It could be a PSU problem, try booting with alternate RAM?


Okay, but do you know of any sites that have information on how to do these things? That would be really great if you can do that. Thanks.
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June 26, 2011 10:33:23 AM

Erm this site?

Remove your hard drive from the pc,
put it into a working pc,
boot into that pc's windows
access your drive (the good windows will see it as a storage unit)
copy/save your needed data

to try booting with alternate ram, you obviously require some ram of the correct standard I.E. ddr,ddr2,ddr3,
put the 'new' sticks in your system and try booting,
psu replacement is pretty straightforward and as you've built before I wont bore you with details

But this leads me to Moto's Law of data, a little known bit of paranoic wisdom,

If you have useful/sensitive/valuable/irreplaceable data on a system,
Back up.
Back up the back up.
back up the back up on a flashdrive
back up the back up of the back up on an external drive
several times so you have a few copies on the external, just in case
:p 
hope this helps man,
Moto
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Best solution

June 26, 2011 12:03:47 PM

Good advice from Moto.

To troubleshoot the old computer, try breadboarding.

The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

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, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

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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June 27, 2011 12:35:19 AM

Thanks for the answer. Even though the computer is back to normal, this information is really great to have for reference and I'm planning to back up everything that is important on the computer. I'd like to give all of you three a "best answer" but there can only be one! So, thanks for being so responsive!

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June 27, 2011 12:38:06 AM

Best answer selected by Steel Ball.
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