Big problem 9500 G graphics card

Hello everyone,
I come to you today to present you my big problem!
I have a 9500 G graphics card (so connected to the PCI Express port of my computer) (not detected by Everest).
My motherboard is not recognized by Everest. "Unknown"
My computer does not work anymore.
I made several attempts.
This does not come from the graphics card because, I tried with another card. Still no signal.
By cons, if I use the video output on the motherboard (GeForce 7050 integrated), then it works!
But graphics cards plugged into the PCI slot does not work!
Why?
Thanks.
