Crash and then, GPU not detected or broken GPU ?

[fluti]

Hello !
My config (working well since 1 year):
- Intel Core i5-4670K (3.4 GHz)
- Gigabyte GA-Z87X-D3H
- MSI GeForce GTX 660 N660 GAMING 2GD5/OC
- Fractal Design Define R4 Black Pearl
- TP-LINK TL-WDN4800
- LDLC TA-750 Quality Select 80PLUS Bronze
- Kingston HyperX Beast 8 Go (2 x 4 Go) DDR3 1600 MHz CL9
- Arctic Freezer 13
- Crucial M500 120 Go

And Yosemite 10.10.2

Here are the facts :
Back to work this afternoon, my computer doesn't wake up, so i reboot it with the reset button on front.
Reboot normally, but it crash 5 minutes later. No kernel panel, nothing, just freezed and no sound.
Reboot it a second time, and a third, and so I suspect Chrome (and Flash).

So i close Chrome and go to play WorldOfWarcraft maybe 4 or 5 hours whitout anycrash. Before to sleep, i just check facebook on Chrome again and crash 2 minutes later.

But this time, impossible to reboot, black screen and "nothing detected" on screen. Panic in my head, i try many thing, checking RAM, checking GPU, reboot, unplugged all USB and other, etc. Nothing.

So I reset Bios with Clear Cmos. I plug my first display on the motherboard, my second display on the GPU, see the bios panel, reconfigure it, i reboot normaly again and infornunatly, just my first display work.
I've try many thing, my two display on the GPU, nothing…


So i'm completly lost, too noob to check why it's doesn't work, or if the GPU is bork forever. (Their fans are working). Thank you for your help guys.


(Sorry for the mistakes, I 'm not English)

 

[fluti]

THere is my boot.plist :

<dict>

    <key>EthernetBuiltIn</key>
    <string>Yes</string>
    <key>GraphicsEnabler</key>
        <string>No</string>
    <key>IGPEnabler</key>
    <string>Yes</string>
    <key>Kernel Flags</key>
    <string></string>
    <key>Legacy Logo</key>
    <string>Yes</string>
    <key>Timeout</key>
    <string>2</string>
        <key>HDEFLayoutID</key>
        <string>01000000</string>
        <key>GenerateCStates</key>
        <string>Yes</string>
        <key>GeneratePStates</key>
        <string>Yes</string>
        <key>UseKernelCache</key>
        <string>Yes</string>
        <key>HDAEnabler</key>
        <string>Yes</string>
</dict>

 

[fluti]

Ok, so this morning everything work like a charm for no reasons.
The two display works on the GPU.

But i try to reboot. And now i'm stuck on the grey screen.

I tried to boot with -x -f -F etc, but nothing. The verbose stuck at "the iousbfamily did not received enough extra current" or something.

Can't boot at all. Any suggestion ? Thank you