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PC not posting - Help Please

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October 30, 2010 4:09:33 AM

Hello all,

My computer I've built and had for about 4 years decided not to post today. I was literally using it last night too.

I powered it on and all fans came on but there was no posting beep. The fan that is on the 4870 i have was running probably at 100%. My monitor would could not recognize anything and keyboard and mouse were not working.

I disconnected all the peripherals (HDDs, Graphics card, optical drive) and performed the following:

- I went ahead and took the battery out and left it for about 10 minutes. Didn't work.
- I performed the reset with the clear cmos jumper. Didn't work.
- Took out all RAM. With all RAM out it did not beep at all for the RAM error. Replacing ram a stick at a time did nothing.

From what I've researched it may be the CPU or motherboard mainly because of no beeping when there was no RAM at startup.

Am I missing anything or what are the thoughts out there in the community on this? Thank you!

More about : posting

October 30, 2010 4:16:43 AM

bcomputinyo said:
Hello all,

My computer I've built and had for about 4 years decided not to post today. I was literally using it last night too.

I powered it on and all fans came on but there was no posting beep. The fan that is on the 4870 i have was running probably at 100%. My monitor would could not recognize anything and keyboard and mouse were not working.

I disconnected all the peripherals (HDDs, Graphics card, optical drive) and performed the following:

- I went ahead and took the battery out and left it for about 10 minutes. Didn't work.
- I performed the reset with the clear cmos jumper. Didn't work.
- Took out all RAM. With all RAM out it did not beep at all for the RAM error. Replacing ram a stick at a time did nothing.

From what I've researched it may be the CPU or motherboard mainly because of no beeping when there was no RAM at startup.

Am I missing anything or what are the thoughts out there in the community on this? Thank you!


If you arent getting a beep, it could quite possible be a fried mobo... go look at your user manual and see if it tells you what it means for no beep at all. But to me it sounds like fried mobo. Some older motherboards caps will go out over time. Its not like today where it can go 50,000 hours strong.

Oh and also make sure your voltage switch isnt moved on your PSU.
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October 30, 2010 4:38:54 AM

Yeah, I do have a Gigabyte P35 board that I bought in October 2006. I've had fairly heavy usage over the years, probably on for 3-6 hrs per day. The manual does not say anything about receiving no beeps.

My power supply doesn't have a voltage switch, so I'm good there. I checked the tops of the capacitors but am not really sure what I am looking for. There are a couple that look as though the lettering is starting to fade near the CPU. Is it easy to tell if they've gone bad?

Thanks!
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October 30, 2010 7:13:44 AM

bcomputinyo said:
Yeah, I do have a Gigabyte P35 board that I bought in October 2006. I've had fairly heavy usage over the years, probably on for 3-6 hrs per day. The manual does not say anything about receiving no beeps.

My power supply doesn't have a voltage switch, so I'm good there. I checked the tops of the capacitors but am not really sure what I am looking for. There are a couple that look as though the lettering is starting to fade near the CPU. Is it easy to tell if they've gone bad?

Thanks!


No, it doesn't mean the caps are bad and only 3-6 hours a day isn't to bad really.

Read this tutorial and go through all of it, i think it will help you.

http://www.techspot.com/vb/topic53866.html
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a c 122 B Homebuilt system
October 30, 2010 12:22:05 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 beeps 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.l

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:
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...

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.

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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October 30, 2010 7:17:48 PM

Thank you for all the information! At this point I think it may be the Power Supply. I got to the part where I bridged the green wire and a black wire with a paper clip to start up the power supply. Here were the results:

- Power supply fan seemed to want to spin, but was barely spinning.
- 120mm case fan hooked up did the same thing, wanted to spin but would barely get anything

So both fans seemed like they'd get a big of power for a sec then die off again.

Also, I did just notice when I did the breadboard that there are (3) red led's that light up on my 4870 card and they stay on, plus the fan on the gfx card is running at like 100%.

So what do you all think? After all that testing this is what I'm thinking now. Thanks!
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November 5, 2010 1:50:36 PM

So I determined that the problem was the power supply and ordered an XFX750 from newegg.

Got it in yesterday, hooked it up and computer posted no problem. I had just recently purchased a new 24" monitor, additional hard drive and also overclocked my cpu, so I'm thinking maybe that pushed my old PSU over the edge.

Thanks for all the help on this!
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