Hi all, since around April 2020, my card sometimes sends no signal to my DisplayPort-connected monitor when I wake the PC up from sleep. I've had the card since November 2017 when I bought it secondhand from a trustworthy source. It appears to have the original BIOS: 86.04.17.00.80), but as I understand it the available firmware update just changes the fan curve (it may well be that somehow over the years there's been damage due to insufficient cooling due to that, however).
 
I can always wake up the card by hitting the PC's reset button momentarily, then it starts sending a signal (and the PC is only woken up, not restarted) and it appears to function normally.  I've changed the DP cable and also ascertained that the problem is with the card because when it's happened I've connected another monitor to the card and sure enough, still no signal.
 
Anyone else experiencing this?  I saw the stickied post about DP 1.3 and 1.4 monitors, but my monitor is the ASUS ROG PG279Q and uses DP 1.2.
 
Thanks in advance for any replies/experiences. I want to keep this thing going till buying a new card at a reasonable price becomes possible again.

Thanks for the reply. I didn't know about the link state thing, good to know and I'll check that. Needless to say "deep sleep" in the monitor settings is disabled for both HDMI and DisplayPort. I checked for the other monitor setting you mentioned and there's none like that. Assuming that's to auto-detect the source? With the ASUS PG27NQ that's not a thing-- you have to explicitly pick an input every time.
As to your other questions, sometimes I put the PC to sleep manually (Windows+X, then U, then S) and then turn off the monitor, or other times (in the evening) I stream something from my PC through Plex but leave the monitor off, then let the PC go to sleep after an hour or so idle time.
 
If it is in fact down to just Windows being Windows, it's weird that it should have just started up like that after having no such problems for the 2.5 years between when I bought and installed it, and when the problem began. I suppose it could have been due to some update.

My monitor only does DP 1.2, so that shouldn't apply, right?

Is this firmware update for all of the EVGA 1080 cards? Does it require the earlier firmware update (the fan curve one), question for anyone?

Really don't want to run the risk of bricking my card, but if it's not meant for my card I hope the installer detects that.

Papageno
Is that the same as setting the Link State to "Off" as @wmmills suggested?  I tried that before and still got the problem. Anyway, I grit my teeth and applied the firmware update from nVidia that @HeavyHemi suggested (although I was paranoid the whole time during the update that there would be a freak power outage at precisely the wrong moment which would brick my card, but thank goodness there wasn't).   We'll see what happens. I could also open the case and make sure the card hasn't somehow had one of its power connectors jostled slightly loose, or become less than perfectly seated in the slot.

This is always a good first step for troubleshooting for issues like this. Another thing, with the age of the GPU, it would not hurt to clean the PCIe contacts on the GPU using a pencil eraser, cotton swabs and 90%+ IPA. You don't need force, just polish off any tarnish, clean with swabs and IPA.  Make sure the PCIe slot is clean, blow it out with canned air if you have it. 
Using GPU-Z, you can check the voltage on each of the inputs to see if you're getting a voltage drop from a high resistance connection.
I have never had to mess with the PCIe link states. I use the High Performance power plan with the min processor percent to 25%...which is the min clock state for the BW-E processor.  I disable the sleep timers for everything.  My system reliably sleeps and resumes in seconds so there's no reason to use them. If I'm not on the system I generally put it to sleep.
And... I have a 2500VA UPS for the outage worries.

Papageno
Figured I'd update this thread. Ended up scoring an EVGA 3060 Ti secondhand (but new!) for a non-scalper price from a fellow regular on another forum (he was in a queue, then scored a used 3070 in the interim) and have not had a recurrence of the issue so I think it was down to the card somehow. I'd have to inspect the contacts on the 1080 as @HeavyHemi suggested, but for now everything is fine.

Glad this is resolved for you.