Graphics Card Issue

[Ghost+6]

I'm having this issue with my 2 Graphics Cards (GTX 780 FTW's) my PC randomly went to a black screen yesterday, i rebooted my PC to notice that it would get stuck loading on the windows 10 loading with the dots going in a circle, it would freeze half way through, causing me to have to restart the pc, i put my PC into Safe mode, and it worked perfectly, i uninstalled the Nivida Drivers, and then i rebooted, it worked, but then every time i would try and install new drivers wouldn't matter which one it would be it would do the same thing.

So i decided to test the graphics cards out, testing them individually, it turns out, GTX 780 #1 works perfectly by itself, but when i go to try out GTX 780 #2 by itself, for starters it doesn't let me go into Nivida Control Panel, with #2, and it displays a really weird blue lines up and down my screen, and it also turns off the display occasionally, 

after figuring out what the problem is i believe its graphics card #2, but i was wondering if anybody else has any other ideas, maybe I am doing something wrong, i have had it working for months now its just something happened yesterday with it, does anybody think the card is dying or no point in using it anymore, because at this current stage I'm considering getting a new graphics card (GTX 1080)

thanks
my setup

i7 4790k
16gb ram
GTX 780 sli (x2)
750W PSU

[Himommies]

Is your Sli bridge plugged in correctly.Try putting Gpu number 1 in the slot for Gpu 2 to confirm it's not a Pci slot issue

[Ghost+6]

1 minute ago, Himommies said:

Is your Sli bridge plugged in correctly.Try putting Gpu number 1 in the slot for Gpu 2 to confirm it's not a Pci slot issue

yeah i've tested it out, i believe its the card not the PCI slot, because One of the cards works fine on it, but the other one has the issues

[Himommies]

Dust maybe or possibly it just broke for some reason

[Ghost+6]

1 minute ago, Himommies said:

Dust maybe or possibly it just broke for some reason

ill try dusting it out, see if i can get it working properly 

[Ghost+6]

sadly dusting it out didnt seem to work