G-SYNC would be a DP 1.4 Vesa Certified cable.
 
The only reason to think about using an HDMI 2.1 cable would be with a 4K TV that has HDMI 2.1 Ports and 120Hz refresh rate and can handle 120 FPS.

Unless you have a 4K 120Hz Gsync TV (such as the LG C9 or CX), DP out is still the typical choice for PC use.

And while game crashes aren't a typical result, black screen flickering for this new HDMI 2.1 standard is very commonly caused by the cable. DP problems can still happen with a DP cable, but it's less common.

If you are like me the only way to get 4K at 120HZ is to use the HDMI 2.1.  
I can say the 8ft 2.1 one from monster is working great for me.
 

Sweet thanks 

yaggaz
 
Okay I cannot work out what DP I currently have. It's blank with no details on it but I assume 1.2 as it came with the monitor.  What is a good 4 to 6 foot vesa certified 1.4 brand you'd recommend?

 
This is one that I am using now.
 
https://www.amazon.com/gp..._s00?ie=UTF8&psc=1

Okay thanks.  Does length affect single or such?

 
Okay thanks went for the 10 footer. I love that snug and warm feeling of being prepared for a new card ;-)
 

I originally went with a 10 foot, thick (looked well shielded) HDMI 2.1 cable. It worked for a week, then started having issues. I put EMI chokes on and rerouted the cable further away from the GPU/PSU and that helped get rid of most, but not all, of the screen blanking. In the end I had to use a 6 foot cable instead. Even though it's thinner and doesn't have any EMI chokes, it doesn't pick up that same interference that the 10 foot cable did (shorter, doesn't pick up the same frequencies).

 
Got the new cable.  Interestingly the first time I connected and booted I got the Four beep motherboard sound and no display coming in.  I switched the DP to the other one on the 2080 and this fixed it.  Of course I put it back to the original DP I tried and it works too.  Odd?
 

yaggaz

arestavo
I originally went with a 10 foot, thick (looked well shielded) HDMI 2.1 cable. It worked for a week, then started having issues. I put EMI chokes on and rerouted the cable further away from the GPU/PSU and that helped get rid of most, but not all, of the screen blanking. In the end I had to use a 6 foot cable instead. Even though it's thinner and doesn't have any EMI chokes, it doesn't pick up that same interference that the 10 foot cable did (shorter, doesn't pick up the same frequencies).

What was wrong?

EMI interference. The 10 foot cable started picking some up that caused the screen flickering - EMI chokes and re-routing the cable helped, bit it still flickered occasionally. Using the shorter 6 foot cable solved that problem.

arestavo

yaggaz
 
Got the new cable.  Interestingly the first time I connected and booted I got the Four beep motherboard sound and no display coming in.  I switched the DP to the other one on the 2080 and this fixed it.  Of course I put it back to the original DP I tried and it works too.  Odd?
 

That sounds like the cold boot no output issue that others have solved by:

Forcing PCIE mode to Gen3 instead of Auto in the motherboard BIOS for the GPU. If your motherboard and CPU support Gen4, then force that instead.

If that doesn't fix it, disable Windows fast boot.

Yeah it only happened once then works perfectly since then. Just thought it strange that it failed on the initial boot up but works non stop after that hehe