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Unknown problem

  • Palit
  • Graphics
Last response: in Graphics & Displays
August 10, 2011 4:22:05 AM

I am not sure if I am in the right place this question, but here goes.

For several years now my computer worked fine without major problems, and then suddenly one day when I turned my pc on
there was a "no signal" message displayed on my monitor but windows was booting, as i can hear the Windows startup sound.

I tried reseating everything, but to no avail. I then tried plugging my monitor cable to the IGP of my motherboard and then it worked.

When I got inside Windows i checked my system properties and i saw that my memory got down from 3GB to 1.87GB, then i went to the device manager and there were no problems, I checked the display adapters and saw that my 8600GT video card is not on the list, it was only the onboard graphics that was there.

In my attempts of resolving my problem, these are the things i already tried:

- Updated all drivers

- Cmos/BIOS reset

- Reseating of parts

- Cleaning of contacts from videocard and memory, also cleaned the slots.

- Tested my video card on another computer and it worked on the other pc.

- Tested my monitor together with the video card on another pc, also worked.

- Tried a new video card (9400GT) on my pc, the results are the same but after a few restarts it worked with the videocard being detected in the display adpater list but my memory was still the downgraded to 1.87GB from 3GB.

- Replaced my motherboard, as i thought it was a pcie slot problem but it did not worked the results were still the same.

- Tried another power supply a slighty higher one (550W), still did not work.

- Tried connecting my pc to another monitor, still did not work.

- Tried also replacing the monitor cables, did not work.

- Lastly, disconnected everything from the case and placed the motherboard together with the parts on a cardboard, still the same it did not work.

I am now wondering what could be the problem, I tried different forums and there were not able to help me resolve this issue.

Any help would be appreciated as I have no ideas left what to do with this. I tried replacing my motherboard to a new one but it still did not work, so i would like to ask you guys here first before replacing anything, as i can't spend anymore money knowing that in the end it would still not work. Thanks in advance.


- Amd Athlon 64 X2 4800+ 2.5GHz
- 2GB Ram
- Palit GeForce 8600GT Super+1GB
- Asus M2N-VM DVI
- Generic PSU 500W (Tornado)

More about : unknown problem

August 10, 2011 2:48:01 PM

Breadboard the system. Then build and test in sections.

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.

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 (standby power supply): 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.

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.
September 6, 2011 9:16:29 PM

Sorry for the delayed reply, I was on a vacation for a couple of weeks. I just tried the breadboard method and the results were these:

- While the CPU & HSF, case speaker, and PSU are installed i heard no BEEPS.

- I tried a different PSU a slightly higher one (550W) and the results are the same.

- I could not acquire a DMM, so i tried the paperclip thing you mentioned with just the PSU plugged in and the PSU turned on flawlessly.

I'm not sure of what part is exactly defective here, now I am using my onboard graphics and checked the device manager but my pcie graphics card isn't still listed there.
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September 7, 2011 5:34:03 PM

Did you re-install Windows when you replaced components? Try to run off a Linux Live CD and see if it will detect the video card. That should rule out hardware issues. That actually would have been a good first start before you tried the hardware testing.
September 10, 2011 12:01:10 AM

Yes I did a clean installation of Windows, I also did it using 2 other hard disks.
September 12, 2011 2:08:04 PM

I think from your list of things to try, the only thing that was not replaced is the CPU. And maybe RAM, don't see a note in here about trying new or known good used RAM. And it looks like you did a BIOS reset, is there a BIOS update you can run?

Try it with another OS maybe, although that may not help you with getting it running the way you want, at least it will help with seeing if it's just an odd Windows interaction with your components or a hardware issue. One of the Linux Live CDs should work for this, no need to install anything else on the drive, just run it off the disk. I do think that that way will provide 3D acceleration to the system.
September 12, 2011 11:05:13 PM

Yes, you're right that the only thing i couldn't replace because all of my friends are using Intel. I already did a BIOS update and now my BIOS is up to date.

I'm not familiar with Linux, where could i find this Linux Live?
November 23, 2011 7:55:19 AM

sorry for the very late response for I went out of the country for a few months...

Back to my problem I still got the same results I even tried installing Windows 7 64bit and got the same results.

I tried putting an old geforce 7200GS and an old 7300GT video card and both worked, and tried my 8600gt on another computer and it worked on the other machine.

Then I tried to put back again my 8600gt on my computer same results but now the fans of the video card are spinning so fast that it was like its about to come off. This problem is freaking me out :pt1cable:  still any ideas?

Only thing i can't replace is the CPU and the memory, do those two could also cause the problem?