First time builder and this has been a serious headache for months now. This problem started back in early September. I replaced my EVGA GTX 760 with a new EVGA GTX 1080 Ti SC2. My monitor would start flashing meaning my screen would go completely black for a second then back on and off. The only remedy is to turn off the monitor then back on until it happens again. I went to my local shop where I bought the card and they said they would RMA it. 7 weeks later the 1080 Ti can't be "fixed" so I get a store credit. I purchased a Asus Rog Strix 2080 and didn't encounter this problem but had wicked coil whine. Exchanged the Asus 2080 for a EVGA RTX 2080 XC and the problem is in fact back. My GTX 760 does not have this problem, it's only been new cards...
 
Troubleshooting steps so far:
- Updated mobo BIOS firmware to latest version
- Downloaded latest monitor driver from Dell
- Thread somewhere said that disabling CSM in the BIOS would help, not the case for me
- Latest Nvidia RTX driver installed and reinstalled
 
I'd share a video of what the monitor flashing looks like but I can't because I'm still too new to the forums so I can't add links. It just looks like the monitor is turning off and on.
 
Set up:
i7 8700k
Asus Rog Strix Z370-I
32gb Corsair Vengeance Ram
Corsair SF600 Gold
Dell U2715H 27" IPS monitor

Are you on a single or dual monitor config? I had 2 2080 and a 2080 ti all had flickering / horizon screen tearing issues. My current 2080ti only has this problem outside games (on desktop) and only when my 2nd monitor is connected. For current drivers this seems to be a know and unresolved issue with Gsync dual monitor but mine is not... Not sure this helps...

Maybe try another display port cable. I have the same PSU (SF600) and my 2080 ti works fine.

Give this Driver a test run GeForce Hotfix Driver Version 417.58
Are you using Both PCI-E Connectors that came with the PSU or just One?
Being that your PSU is under the Minimum 650 Watts you NEED to use Both Cables.

Requirements

• Minimum of a 650 Watt power supply.
• Two available 8-pin or 6+2pin PCIe power dongles
• Total Power Draw : 215 Watts

Requirements

• Minimum of a 650 Watt power supply.
• An available 6-pin PCIe power connector and an available 8 pin PCIe power connector
• Total Power Draw : 215 Watts

 
Your older GeForce GTX 760 card Only needed 500 Watts.
https://www.geforce.com/hardware/desktop-gpus/geforce-gtx-760/specifications
Minimum Recommended System Power (W) 500 W
 
 You need to buy a New PSU. I would recommend this one
EVGA SuperNOVA 750 G3, 80 Plus Gold 750W, Fully Modular, Eco Mode with New HDB Fan, 10 Year Warranty, Includes Power ON Self Tester, Compact 150mm Size, Power Supply 220-G3-0750-X1

Duder10

bcavnaugh
Give this Driver a test run
Are you using Both PCI-E Connectors that came with the PSU or just One?
Being that your PSU is under the Minimum 650 Watts you NEED to use Both Cables.
 
Your older  card Only needed 500 Watts.
Minimum Recommended System Power (W) 500 W
 
 You need to buy a New PSU. I would recommend this one

Thanks for the detailed reply! 
 
I'm using both PCI-E connectors. Since I'm in a SFF case my power supply options are limited and thus the recommended PSU won't fit. I find it odd seeing so many other people with the SF600 and 2080/2080 Ti's and everything is all good. Similar to arnolf above.
 
Some quick googling yields a number of different power consumption results of the Asus Rog Strix 2080 versus the EVGA 2080 XC. No definite answer saying that the Strix 2080 uses less power which is why I may have not experienced those monitor black outs during that week with the card. It's just strange that I'm dealing with this on both the EVGA 1080 ti and now the EVGA 2080 XC.
 
Currently running a test with my PC at idle waiting to see if the issue appears again. Then I'll install that driver and run the same test and see if anything changes. If the issue persists after the driver update, I will move the 2080 into a PC that has a bigger PSU and run the test again and see if that changes anything.

Time for a bigger Case or wait for the RTX 2060 or even the 2050 Card.

I just got a Acer XB271HU delivered in the mail today actually and will try out the new monitor and see if it occurs on this one. Going to be doing a lot of troubleshooting today and I'll post back here with findings. 
 
Thanks for your continued support everyone!

Duder10
Long overdue update, I wanted to post with the answer if anyone stumbles across this thread.
 
My last post I said I got a new monitor, it pairs very nicely with my EVGA 2080 XC. No Flashing issues compared to the Dell U2715H which was still suffering from this problem. 
 
The Dell monitor was using a Display port to mini Display port cable which came with the Dell monitor. I purchased an Accell Display port cable, replaced the Dell provided cable and the flashing on my monitor has stopped. Turns out it was a cable issue the whole time.