Replace my entire PC - still black screening.

Maybe beacause it was running in windowed 1280x720 with no anti aliasing ? i clicked on "GPU stress test" maybe i had to click on preset 1080 ?

Sure, 1080 preset should do it. Windowed or not wont matter much.
Does your PC stay responsive when this black screen happen? You said you could hear the sound going, does it, say, continue shooting if you click the mouse in a FPS game etc? Tried a different monitor? Do you have an LCD TV perhaps you can try? Also a different cable?

no it's completly not responsive, i just have to push reset, also i don't have background sound, it was the first time, i don't remember exactly but i don't have any sound.

Yes i tried different monitors HDMI/DVI to vga

also here is with 1080 presets, didn't crashed but it runs only like 2 minutes before he finished, so i will run it in stress test in 1080p with anti aliasing at fullscreen
http://puu.sh/kbeGo/eae45c7d9c.png

after running it at fullscreen, the gpu clock was at 1084 max instead of 980, and i seen artifacts but no crash, the TDP / gpu usage was at 99%/100% , looks like 1084 mhz is the JUST limit before black screening (furmark wouldn't go past 1084, idk why), but why it would surprinsingly happen after a driver update ? Why a sudden decrease from 1200 to 1000 ? Why the 280x does the same thing ? so weird...

Sorry about the sound part, too many threads, I got confused :)

Well, did you change to the same motherboard model when you did?

Since you suspect it: Did you check your CPU pins? maybe one of them got broken
Did you stress test CPU? Intel Burn Test and Prime95 (I see you already did Prime95)

Did you try another power socket in the apartment?

Do you have a dedicated sound card or using on-board?

Nope i changed from a MSI Gaming 7 (Z97) to a Asus Z87 Deluxe (Z87)

My cpu don't have pins ^^ also yep ! when i was switching the motherboard i checked the pins everything was ok !

About the power, it's not my electrical installation, beacause like i said (you maybe not seen it) i launched a game, turned off electricity to run on the UPS, everything was exactly the same.

I don't have a sound card, that's money for useless (my advice) i like excessive excellence but i don't pay attention to sound part, headsets are already costy enough ^^

So we found the "source" that's related to the GPU clock, but why the 280x would black screen too, why do i have suddenly to downclock after these famous windows 10 nvidia drivers (tried everything that was possible, rollbacking, modifying the .sys of nividia in system32 etc etc) we should focus here.

To be honest, whatever I think of you have already tried. So perhaps you should follow your instinct and try with another CPU as well.

Maybe try downclocking the CPU to 50%. You can adjust max and min processor state in power options. And if that works try increasing by 10%. Check with HWInfo or similar to confirm.

Also this gave me another idea, if processor is somehow damaged maybe ... Try disabling IEST, C1E in BIOS.

Can't you work with the importer/distributer of your GPU in France?

If everything fails and you are stuck with it, you should ask the community for a custom BIOS (first ask Gainward directly) which downclock it to your liking.

Maybe one of the below
www.overclock.net
Video Bios Collection | techPowerUp