PC turns on for a second, then dies

[Boaksls]

Hi guys I really need help.

My computer has been working fine with the current setup for 6 months now. Just yesterday, I decided to open up my case to do some maintenance.

Problem:
-When I finished, I pressed the power button and my system turns on for a millisecond and then turns off.
-Pressing the power button again has no response.
-Restarting the PSU and pressing the Power Button will give the same "turn on for a millisecond" response. My PSU is a Corsair TX750 750Watts.

I disconnected my graphics card (Radeon HD7950) from the PCI-E slot and PSU and the PC boot successfully with everything running fine. So I when into the BIOS and loaded the fail-safe defaults. I re-installed my graphics card and my PC would turn on for a millisecond again. I disconnected the two 6pin PCI-E power connectors from the Graphics card but left the card in the Motherboard PCI-E slot. (I know that's bad because I'm not supplying enough power to the card). I pressed the power button and everything boots with success. But whenever I plug the 6pin connector into the graphic card, I have the same millisecond problem again.

Motherboard is Gigabyte GA-Z68x-UD3H-B3 rev1.3

I took out my old graphics card (Radeon HD6850) and installed it into my build. Everthing went perfectly and there were no problems. So I concluded it's not a faulty PCI-E slot. It looks like a PSU problem because the 7950 needs 2 6pin connectors while the 6850 requires only 1 6pin. But then I have a good 750 watts so I should have enough power.

Stuff I have connected:
- 1 SSD, 2 Hard Drives
- 1 DVD Drive
- 4 case fans
- 4 sticks of RAM
- 1 Internal Card Reader

750 Watts should be enough for the above AND a 7950 right? I've been running this EXACT setup for 6 months without a problem.

What I did in my maintenance:
- Cleaned out dust
- Made sure wires were connected at the right place and not loose
- Removed my Cold Cathode Lighting stuff
- Installed an additional fan

I really hope it's not my 7950 that's causing the problem. I spent a good $450 on it and I can't afford to replace it. I'm still a student.

 

[mac_mac_attack]

When you boot it with the card plugged into the PSU does the card
beep a lot? Cards usually have an alarm that goes off if the power requirements are met. 750W is obviously plenty unless it's malfunctioning.

 

[Boaksls]

When you boot it with the card plugged into the PSU does the card
beep a lot? Cards usually have an alarm that goes off if the power requirements are met. 750W is obviously plenty unless it's malfunctioning.

No, there were no beeping while the card was in. When I took the card back out for the first time, the motherboard beeper had a continuous long beep. After I loaded the fail-safe defaults in the BIOS, the beep went away.

 

[smorizio]

check the pci slot for any dirt or dust or bent pin. also check the video card for any damaged pins. if your mb has two video slots try the other slot. i wold also check under the mb to see if there a screw or that with the video card installed the mb is bending down and shorting out. the other thing to check is there any wires near where the video card plugs in you could be cutting or pinching a wire now. also check to see if any of the video power cables are cut or shorted.

 

[Boaksls]

check the pci slot for any dirt or dust or bent pin. also check the video card for any damaged pins. if your mb has two video slots try the other slot. i wold also check under the mb to see if there a screw or that with the video card installed the mb is bending down and shorting out. the other thing to check is there any wires near where the video card plugs in you could be cutting or pinching a wire now. also check to see if any of the video power cables are cut or shorted.

thanks for the advice. But still no good. I tried inserting the card in another PCI-E slot but still the same results. What's weird is that the the system won't start even if the card is taken out of the motherboard but still connected to the PSU with 2 6pin connectors.

 

[dudewitbow]

if your cpu has an IGP, try taking out the gpu and booting the computer using the IGP alone. if it works, then its the pci slot/gpu/or psu problem thats happening.

 

[Boaksls]

I think it is the Graphics card that's causing the problem. I installed my 7950 into my friend's PC and it caused the same problem. His PC would turn on for a millisecond and turn off. He has a 1000 Watt power supply and he took his two geforce 580 out of his motherboard and replaced them with my 7950.
I'm so pissed right now because I spent so much on my 7950 and now it's dead. Barely had it for 6 months.

Thank you everyone for your help

 

[Boaksls]

Best answer selected by Boaksls.

 

[smorizio]

hopefully it one of the cards with a one year or longer warranty and you can rma it to the vendor.

 

[booze99]

I had the same problem after adding an ssd. It turned out the cpu heatsing/fan assembly got slightly dislodged and didn't make good contact with the cpu. This allowed the pc to boot for a few moments, then die without a beep or other sign. I'd also check this before RMA'ing components. If you go in the bios settings you may be able to monitor CPU temperature real time from there and see if it keeps on rising before the pc shuts down.