My latest mining rig consists of a MSI Z270A PRO with a Celeron G3950 CPU and a couple of 8GB sticks.  It has 6 EVGA 1080Ti cards (11G-P4-6393-KR) with the needed risers, etc.
 
I have power on the 1080Ti's set to 65% and the whole rig is pulling between 1090 and 1130W depending on what is being mined.
 
It has been rock solid for over a week, but I'm just wondering if I'm going to have issues down the road pushing it this hard?  I know tests have been done showing that it will put out about 1,333W, so if that is the true max capacity, then 1,100W is about 82% load, which is pretty close to the general rule of thumb not to load a PSU more than 80%. 

Nobody is going to be able to answer this question.

pclausen
Have there been any durability tests done on EVGA power supplies being run at close to their rated capacity for extended periods of time?

Not that I know of, but I didn't go looking on google for the answer. Looks like you didn't find anything on google, so I'll most likely get the same results.

mostly all ratings are based off intermittent loads and nothing electrical is meant to be ran over 80% load for 24/7 use.

i have always looked at the Amps from the wall and not the load.

rofl, at this rate with AMD going back to 300W power monsters nvidia may do the same. granted those 300W cards are basically as powerful as nvidia's 180W TDP 1080..... soooo, then again maybe not.

I picked up a "drop in cage" kit from a guy over on bitcointalk, so that made it all very easy.  Yep, I believe that is 8020 bar stock.
 
So I picked a SuperNova 1600 P2 so that I can crank those 6 1080Ti's up to 75% ish power hopefully get up around 700 Sol/s per card or 4,200 Sol/s for the whole rig.
 
I'm also going to cut a hole in the side of the case and flip the PSU so that it pulls in cool air from the outside instead of hot air that has been blown across the GPUs.

Quite a few folks have run the EVGA G2 1300 at a high load percentage for extended runtimes on ASIC_based mining gear - but the load those ASIC machines present to the power supply tends to be less variable and "spiky" than GPUs present.
 
 I'd be inclined to not push even a GOOD power supply like the P2 1200 much past about 1000 watts in 24/7 service in a GPU rig.
 
 Your plan to flip the PS and if you make the hole at least the size of the fan and make sure you line it up well should help on longevity by keeping the PS cooler.
 
 I'm not 100% certain, but I suspect that there are already 300 watt current-gen NVidia cards - AIO versions of the 1080ti and possibly the TitanX/TitanXP.
 
 I've not OWNED one but I'd be somewhat shocked if NOBODY had built a 3'd party card with a higher TDP than the NVidia "standard" 250 watt limit (I WAS shocked that the TDP on my Aorus is 250 watts).
 MSI for example has at least one model of 1070 with a TDP in the 220 watt ballpark, even though NVidia calls for 151 watts on those....