TRITIUMNITR0X

I have an update! The XMP profile finally worked.
 
After trying different settings / clearing CMOS over and over, it seems that flashing the BIOS opened a new avenue to allow the system to XMP more recent memory. In addition to the memory, I was also able to overclock the CPU to 5.0GHz and overclock both 1080Ti's in SLI, achieving a +25 FPS gain in Heaven Benchmark after all things were said and done.
 
As an addendum, I should note that both before and after the BIOS flash, I was completely unable to manually overclock the memory, even with the recommended speed, timings and voltage given by the XMP profile. I suppose the XMP profiles contain much more intricate settings than previously assumed.
 
I'd definitely consider this a success. Thanks @Super panda @aDoomGuy @Arika S for the help!

I have an update! The XMP profile finally worked.
 
After trying different settings / clearing CMOS over and over, it seems that flashing the BIOS opened a new avenue to allow the system to XMP more recent memory. In addition to the memory, I was also able to overclock the CPU to 5.0GHz and overclock both 1080Ti's in SLI, achieving a +25 FPS gain in Heaven Benchmark after all things were said and done.
 
As an addendum, I should note that both before and after the BIOS flash, I was completely unable to manually overclock the memory, even with the recommended speed, timings and voltage given by the XMP profile. I suppose the XMP profiles contain much more intricate settings than previously assumed.
 
I'd definitely consider this a success. Thanks @Super panda @aDoomGuy @Arika S for the help!

Hey W00sh,
 
As a user who bumped up from a 980 Ti to a 1080 Ti utilizing the same system, I had an apples-to-apples comparison of the two cards.
 
Depending on the game (I assume you'll want to play modern GPU-intensive games), and assuming you have the graphical settings maxed out in 1080p as I do, I can tell you that the non-OC'd 980 Ti has hiccups and frame drops far more frequently than the non-OC'd 1080 Ti. It's obvious that there's that difference, but I say it to make a point clear. Your 980 Ti will not run at 144 fps with modern, GPU-intensive games, at 1080p, and even more so at 1600p or even 1440p. The 1080 Ti, however, is able to run 144 fps at 1440p, but not stably. It will swing between 90-120 FPS for the most part, and spike to 144 fps very infrequently- when there's low-med load. The only true means of obtaining 144 fps semi-continuously, is by using SLI with paired 1080 Ti's. And even with that, which I have now, most games run stably at around 130 fps.  Keep in mind that lot of games, however, do not support SLI. And even more to the point, you'll be staring down at an empty wallet after purchasing your second card. Trust me, it's a conflicting feeling. On one hand, you have two 1080 Ti's, while on the other hand, you have enough money for a small fry at McDonald's that has to last you a week.
 
There's rumors about the 1100 series releasing at the tail-end of 2018, but the CEO of NVIDIA has stated that the series will not be release for some time coming. Dates are only speculative.
 
Tl;dr: Do what you want with your money, but don't expect miracles from the 1080 Ti just because it's expensive. It will blow your 980 Ti out of the water, but you won't be given the experience you're seeking.

Thank you for that insight. I had no idea that MSI voids warranty on upgrades.