You'd just have to use gpu-z, or nvflash to backup your original vbios before updating to a different vbios. Nvflash can reflash the old one back when needed.

I thought I'd chime in too, since I've noticed this issue since I got my 2080ti several weeks ago. I am using a Gigabyte 2080ti Gaming OC, but searching the web I found posts from people with asus/msi/evga/Fe cards all showing the same problem.
 
In my case my card's default power limit is 300w, I can very easily make the fans go to 4000rpm if I crank the power limit to 366w, as soon as core temps go above 76 degrees the fans ramp up to 4000rpm and stay there until temps fall below 76 degrees. Now at stock power limit of 300w, the card will ramp fans when the temps are 78-80 degrees, the trigger point isn't an exact temperature but dependent on the app. Heaven with it's erratic power load draw seems to trigger this behavior at 78 degrees, furmark does it at 79 degrees and in games like witcher/mordor/bfv it's around the 80 degree mark. The fans burst up to 4000rpm for a second, core temp drops a degree or 2 and then the fans go back to normal rpm. This just repeats if the power load is constant.
 
While this is occurring the fan controller still says the fan speed is 80%. This problem goes away if I set power limits to 280-290w. If I lower fan speed manually, core temps can rise to 82 degrees before I see this fan speed ramp appear again.
 
I've tried different bios, the last 3 drivers and this behavior still persists. I don't believe the fan controller is capable of understanding power draw and temp to figure out the fan speed, so I believe this is being done in the drivers. There is some clever algorithm looking at power draw and temp deltas to determine whether to trigger this, way to complex for a fan controller chip.
 
My theory is nvidia quietly put in this turbo mode to keep core temps below 80 degrees with high power draw, We already know there are A and non A binned chips and the non A can't do more than 280w so the poorer silicon has limits at high power draw. We see the max temp limit is now 88 degrees instead of 90 on 1080 series. I have seen how power hungry the 2080 series can be where it can sit at constant loads of 300w+ very easily, I've also seen temperature and heat rise exponentially and very fast on these chips at high power limit levels.
 
We never got a good explanation why chips were dying or still continue to die, I believe the 2080 series cores are susceptible to damage when operating at high 80+ temps and high current loads, the chips degrade and or parts of them fail. Because it's such a big core, there could also be part of the chip that run much hotter than the reported temp which is usually a tjunction core avg. 
 
My work around right now is I flashed the F2 bios which has the FE stock 260w limit and 290w max power limit, I find with these power limit levels the fans never ramp up and temps are always in the 70s. In my mind it's unsafe to run 300w+ on air on these chips and it's the reason why so many cards have died.