PC doesn't boot while graphics card power connector plug in

I'm using Foxconn 9800GT-1024F graphics card for last few months. So far it was working with TT550 Watt PSU. Now I'm facing a problem. My pc fails to boot while graphics card plugin. Even no cpu fan movement or PSU starts. But when I unplug the power connector of the Graphics card, then the PC boots with no display and the Graphics card gives long beep for power. But if I connect the connector then PC boots fails. For diagnostic I unplugged the card from motherboard and take the graphics card to my hand and only connect the power connector from psu to graphics card, then still the PC fails to boot. I found when I press the power button both the cpu and graphics card moves a bit but not rotate. then no boot.

So please can anybody help me to solve this issue. I'm guessing some short circuit from graphics card. I'm also an electrical engineer. So if anybody give me some idea about how to repair, I can do it my self.

My system config:

Pro: Core i3 2.93GHz
Mobo: Biostar H55HD
Ram: Transcend 4 GB DDR3
PSU: Thermaltek 550 Watt
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  1. Hi there are a couple of options i am aware of here. One is that your PSU was only just managing to power the card in the first place and has now degraded to the point where it wont do so anymore. It would be good if you had a friend who would let you try the card in his/her pc to test it actually works and its not the card at fault.

    Secondly, i had a very similar issue a good while ago now where i had a system that ran fine and then started doing much the same as yours is doing now. I don't pretend to know exactly how but it did it after i updated the drivers for the GPU.
    Thats a pretty long shot but i thought i would mention it.

    Mactronix :)
  2. Thnx for ur reply. But I have already tried with a different power supply but same problem. Even I have tried with only a separate PSU only connecting graphics card, didn't connected to mobo or any devices but same results. PSU doesn't start.
  3. Ok so if both the CPU fan and the GPU fan dont spin up that would seem to indicate that the issue could be the motherboard.
    Assuming your using a PCIE cable that is fitted to the PSU and assuming that as the PC will at least start without it connected to the card then that is the possible issue here. So did your card come with a 2 Molex to 1 PCIE connection cable and do you have 2 spare Molex connectors to try using that instead of the PCIR cable to power the card ?

    Im not an engineer but im not sure if using 2 different PSU's wouldnt cause an issue itself as i remember reading something about it on line ?

    Mactronix :)
  4. motherboard is not factor. I didn't use any accessories. I just connect the graphics card directly to PSU and tried to ON the PSU. but PSU shuts off
  5. The first thing to do is to try the video card in another computer.

    If it doesn't work, you have found the problem. If it does work, continue.

    Work systematically through our standard checklist and troubleshooting thread:
    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.

    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.

    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.
  6. Now, I found my card is internally faulty. I found in Power connector(6 pin) pin no.1 and pin no. 4,5, 6 are short. as we know the below 4,5,6 no pin are common. So I think the negative and positive power got short circuit and make the psu failure to start. I have checked by a multi meter. So, in this situation can anybody help me to solve this issue? How can I find out the faulty part of my graphics car?
  7. plug it in another PC, try it on a different PSU and Mobo. if tho problem continue. well, bad luck. try sending it back
  8. doves said:
    Now, I found my card is internally faulty. I found in Power connector(6 pin) pin no.1 and pin no. 4,5, 6 are short. as we know the below 4,5,6 no pin are common. So I think the negative and positive power got short circuit and make the psu failure to start. I have checked by a multi meter. So, in this situation can anybody help me to solve this issue? How can I find out the faulty part of my graphics car?

    Droves, I have had this EXACT problem, with an 8800GTS, and now seemingly, a 4770. I think its because some of the regulators near to the power input on the card have gone bad. I can see no solution to this short of changing those - but where to source them? :\

    My issue was particularly puzzling, as this behavior seemed to start occurring with all my "bad" cards. Whereas in the past, they just wouldn't boot, now they were shorting my PSU.

    I'm not 100% sure its caused by bad regulators, but this is my suspicion.

    I too would like a solution. If I find one, I'll share. I hope you will do the same. GPU's are expensive in my country.
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