Swapping gtx 780 to 1080 fail help plz

[XxRustyxX]

Ok so yesterday i bought a gtx 1080 zotca AMP Extreme to change it for the 780 i have, i wasnt bothered to install it the same day as it was night time so i was like ill do it tomorrow, so today i installed it, and when i tried to start my computer it didnt even start, then i removed it to see if it started with the integrated graphics card and it didnt start, then i switched back to my 780 and it didnt start, (i had only 1 ram stick on at the time i was doing this cuz i had to remove 3 of em for easier installing (note that i had my 4 sticks of ram connected when i tried to boot with the 1080) then i added 2 sticks and nothing 3 sticks and nothing and when i finally added my 4 sticks wich basically is how my computer was before i started the graphics swap it booted fine, so my question is how do i install my gtx 1080 without issues? BTW i Overclocked my cpu yesterday from 3.6 to 4.2 and did a stress test and it seemed fine it is liquid cooler with the h110 so that might matter.
Here are my specs if that matters.

Motherboard: Gigabyte z77x UP5 TH
Ram: 16 gigabytes ddr3
GPU: Gtx 780
Power supply: Cooler Master Silent Pro 700W
CPU: Intel core i5 3770k OC to 4.2

[App4that]

Use DDU To remove all drivers. Then install the drivers manually.

[XxRustyxX]

8 minutes ago, App4that said:

Use DDU To remove all drivers. Then install the drivers manually.

Umm sry if this sounds dumb but what you are saying is, remove drivers, remove card, add 1080, install gtx 1080 drivers manually?

[App4that]

Yep. Ether using the IGPU or 780 use DDU To boot to safe mode, once there you will see the option to remove drivers and turn off the PC. Do that. Then install the 1080, and download the latest Nvidia driver being careful to get the 64bit version if you have that. Then choose the custom install option and DO NOT install the 3d crap or GeForce experience. 

[stealth80]

Did you reload default in the bios? 

[XxRustyxX]

3 minutes ago, App4that said:

Yep. Ether using the IGPU or 780 use DDU To boot to safe mode, once there you will see the option to remove drivers and turn off the PC. Do that. Then install the 1080, and download the latest Nvidia driver being careful to get the 64bit version if you have that. Then choose the custom install option and DO NOT install the 3d crap or GeForce experience. 

ok thx i will do that see if that works.

[Mick Naughty]

Just get another 780 and use the 1080 as a paper weight. 

[XxRustyxX]

Alright sry every1 for the wait took me a long time today of trial and error to finally being able to install it, turns out i tought the cables that came with the GTX 1080 could also be able to be used as extensions, ie connecting both 8pin cables from my power supply into them and then the cables that came with it to the gpu, turns out it wasnt working because of that, i had to connect them directly from the powersupply to the gpu using one cable, wich was tricky cuz it barely reached thats why i was using the so called ¨extensions¨ in my mind :P, i however going to have to give the best answer to @App4that as i dont know if i would had have even more trouble if i hadnt done what he said, so thank you, and thanks to every1 else that tried to help me solved this issue.