Hello,
I just recently got an Nforce 780i SLI motherbaoard and I want to set up a new rig of old parts I have.
The parts I am using for this rig are:

• Nforce 780i SLI motherbaoard
• GTX 660
• 2x1 GB ddr3 ram (Hypnix hymp512u64cp8-y5)
• EVGA 450w PSU
• Intel core 2 duo (E8400)
• Corsair H60 liquid cooler

The motherboard turns on fine. I can get into the bios menu and make any adjustments.
However, whenever I try to install an OS using a boot disc or USB it fails. 
Whenever I try to install Windows 7 or 10 it boots up the disc and displays this screen.

(A picture I found of the internet)
However, my computer does not display the loading wheel at the bottom of the display.
After a minute or two of waiting my computer eventually restarts and goes back to the bios.
During the install my motherboard displays FF on the motherboard.
 
Finally, I gave up on installing Windows and I tried Ubuntu 17.04.
I managed to boot up the disc and when I select "install Ubuntu" the screen goes black and the motherboard displays an Fb or F6 error code (I cannot tell the difference between b and 6 on my motherboard).
 
What am I doing wrong?
What does the error code Fb/F6 mean and how can I resolve it?
 
Thanks,

quadlatte
ram seems kinda small for a new OS. try with 4GB if you can

What this man has pointed out;
 
It's thus worth adding that the Windows 10 technical preview has these requirements:
Processor: 1 gigahertz (GHz) or faster.RAM: 1 gigabyte (GB) (32-bit) or 2 GB (64-bit)Free hard disk space: 16 GB.Graphics card: Microsoft DirectX 9 graphics device with WDDM driver.A Microsoft account and Internet access. 
I don't think you would be installing x64 on a 2GB system, and would stay with the 32-bit as you should only having 2gb of ram.
You should be safe regarding that.
 
Is there any possible way for you to test the Power Supply? The reason why I ask because of the FF code being posted on the 780i SLI is usually for shorts\shorting. (FF is usually displayed normally always when you go to boot your system as it powers on)
Try re-doing your power on buttons\reset button\HDD Led connections and make sure they're properly connected, this could be causing the FF code, again the PSU could be doing it as well.
Try bare minimum requirements for an install of an Operating System. Seems to be a short\faulty PSU to me as you pointed out the board is posting fine and you're able to make changes. Try re-seating the BIOs battery and pushing down on it as you re-install the battery before you do a bare minimum install for your OS.
 
Some of this information I found around the forums; https://forums.evga.com/EVGA-780i-SLI-code-FF-no-POST-m494526.aspx
 
You should also save this link incase you no longer own the manual to the 780i SLI since it is a dated mobo; https://www.evga.com/support/manuals/files/132-YW-E178.pdf
It's the manual in a .PDF format, you will be able to look up every code the motherboard throws at you with this manual and make it much easier to pin-point your issue.