Computer doesn't startup when graphic card plugged

Hi guys, I have a similar problem:

Just bought a new PC, installed everything and using onboard graphics, everything is OK. If I plug in the graphic card, the computer doesn't start. The display don't turn on, the keyboard / mouse lights neither. The Fans are working (even the graphic card fans). I unplugged and replugged everything, reseted BIOS, disabled onboard graphics, but with the graphic card nothing works.
I have no chance to test the graphic card on other PC, or other graphics on my pc.
Any help ?
Thanks for your time!

My system:
XFX Core Edition PSU PRO 550W
Gigabyte B75M-D3H
Gigabyte Ati HD7870 OC Version 2GB DDR5 PCI-E
Intel Core i5-3470 3.2GHz (3.6GHz Turbo) 6MB BOX
Corsair Vengeance LP 2x4096MB DDR3 1600Mhz
Samsung 840 SSD 2.5 SATA III 120GB

[bryann]

Well the fact it works when you don't have the graphics card inserted but doesn't when you do sounds like you have a faulty one! Just return it

[aVar++]

I know it's simple but have you plugged the screen cables into the graphics card, not the motherboard connectors?

[rubberman]

A lot of video cards suck up a HUGE amount of power, that many systems' PSU (Power Supply Unit) is incapable of handling - often over 100 watts. You need to verify that your system's power supply can handle the additional load.

I tried to plug the screen on both, motherboard (DVI and HDMI) and graphics card (HDMI and DVI). The simple fact having the graphics cards plugged, nothing works, just the power supply and the fans :).

I've seen people with very similar systems and less powerfull PSUs (450W). I could understand that if after some gamming with graphics on max load the system reboots, but it's on startup, graphics cards isn't doing much yet :)

[BigPaw]

The hardware you list here amounts to just over 480W, is there any other hardware or peripherals we need to know about?

Are you confident that you are putting the card in the correct PCIe slot?

Have you followed all ESD precautions? (This is more important than many people think)

No more peripherals, only the keyboard and the display.
I tried on both available PCIEX-16 and PCIEX-4.
Maybe I didn't follow all the ESD precautions.. but i think i allways touched the case when plugging the graphics card.

[javanoob101]

First of all, that's a feaking good look'n video card (I only have an OEM Nvidia GT420!) but judging buy some pictures i saw on newegg, you may have to plug in external power cable from the power supply... However if you have done this already, and it fails to power on even to bios, it may be you power supply, it may not have enough ommph to supply the computer..

If possible, try to use the video card in another working computer (make sure it has the correct PCI port on the motherboard)

Let us know what happens!

javanoob101

Hello people,
I tried the graphics card on another older computer with an 650W and it works perfectly ! So I think the problem is some BIOS config or a problem with PSU since i tried 2 PCIE slots, what do you think?
Thanks!

PS: I have no chance to try the other PSU on my comp

Hello again,
I tried a Radeon 5770 on my PC and it works perfectly, I'm running out of ideas.
Thanks for any help :)

[javanoob101]

sounds like the psu might be chokeing out...

the older computer has an extra 100 watts which could be the difference here... or, the mobo doesn't support that video card, but that seems unlikely though...
anyway yu can get a bigger psu in the computer? That seems like the last thing to try, because you know that the video card works...

javanoob101