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PC won't boot, beeps loudly when 4 pin atx is plugged in, doesnt display anythin

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May 22, 2011 2:25:19 AM

Hello,

My wifes sister has told me her PC was running really slow, and I was telling her how to do a system restore but she downloaded a virus scanner instead and it wouldnt let her install it or something in safe mode. She rebooted it, and the PC wouldnt come back on.

Soon as you turn it on it starts a constant beep that goes for about 15-20 seconds, it stops for a couple seconds then repeats. The display doesnt get any input, the keyboard lights up when you first turn it on for a sec. All th fans work, including the PCU fan. If I unplug the P4 it doesnt beep, but still doesnt get anything on the display.

I'm assuming the motherboard is shot? I havent really tried anything to try to get it working as im not sure where to start. Can someone give me some ideas? Thanks

Its an hp a6300f

Heres the motherboard:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01...

Best solution

May 22, 2011 3:46:14 AM

what beep sequence does it give.
short beeps are about a 10th of a second, while long can be half a second or more.
depending on the sequence of short and long, it will help pin point the problem.

as yours is 1 long beep. if its an ibm bios then its telling you theres a fault with the power. either a short or loose lead.
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May 22, 2011 5:15:36 AM

yeah these are all long beeps, They are a bit shorter if I hit a bunch of keys on the keyboard while its dong it =P but they are still longer than half a second even then.

Have read on some other sites that its: BIOS: Phoenix - AwardBIOS v6.00PG

It says that its either Memory or overheating on other threads about the pc. Seems a lot of people had the issue with this motherboard, and one person said that the model is defected, but that HP wasn't doing any replacements. I'll try a few things later and see if I can get anywhere with it.

Thanks
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May 22, 2011 4:12:02 PM

May help ...

Work systematically 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.
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 2, 2011 3:36:42 AM

Best answer selected by RLB31384.
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