Did it to my eVGA 2080Ti's after water cooling them. I don't think I will ever not do it again. It improved things greatly on the stock BIOS (1st BIOS was 280W, then update from evga set it to 338W). With the card thinking it was drawing less power (factor of 1.625), I was able to hold higher clocks. With the 338W BIOS I would get 2085-2055 with the typical game/rendering speed settling at 2055 once temps levelled. vRAM was set to 8000 (16000 effective) and forgotten about. Not really an issue if you got the cards with 16Gbit Samsung chips. I got mine through step-up and the serial numbers are sequential and both cards have this memory. I don't know if they failed 16Gbit (2080Ti spec'd for 14Gbit) testing or it's all they had. This was during the whole "OMG MICRON MEMORY IS SO TERRIBAD AND MY 2080Ti SUCKS" phase. Either way, I have never had an issue setting them to 8000 on an eVGA BIOS (XOC BIOS does wonky things with the timings and 7800 is the limit).
Average fps in CoD (MW/WZ or BO:CW) was about 150fps at 1440p high/ultra settings, RTX OFF and DLSS on Balanced. Perfect for my 144Hz display. I can't remember what Cyberpunk was as I have not played it since a few days after launch (I want the game complete and fixed before I play it through), but...nevermind, I found the "New Text Document.txt" on my desktop with the settings. 1440p, Ultra, RTX OFF, DLSS Balanced was seeing 95-125fps in outdoor/open areas and 100-145fps indoors. In both those games I run DLSS even though RTX is OFF because it speeds up the rendering of things or something and gameplay feels smoother. This is with the stock 338W BIOS from eVGA as, at the time, I stopped messing with other BIOS because none of them could support the memory properly. So: In my own personal experience there was a noticeable difference in performance vs no shunt while being able to keep the benefits of the OEM BIOS. In my case the original BIOS was a measly 280W because I went for the lowest class "A" GPU I could find within my means since I was going to water-cool them. Step-up with 2x1080Ti FTW 3's made these cards $680 each, shipped. You just have to be willing to void the warranty of a $1000+ dollar card (or in my case, 2 of them) and be able to accept the consequences of doing such a mod. Not that it needs to be said, but soldering on a couple resistors, beating the card until it dies, removing the mod and then attempting to issue a warranty claim is kind of scummy IMO.
Now last week I got "the bug" again and decided to check the 2080Ti thread here to see if there were any new BIOS files since the last time I visited. Well hello there GALAX HOF OC Lab BIOS that has all the features enabled (Voltage/Frequency Curve Editor & 2D clocks especially). Besides the profile loading issue with MSIAB and Xtreme Tuner (BSOD if you have it set to load a profile on windows load), it's been a great BIOS. An XOC style BIOS with all the limits removed, 2000W PL, but has the nice features? Yes please. Best part is it works with my vRAM and I can set to 8000. This BIOS makes the shunt mod unnecessary, but makes water cooling mandatory. I still haven't fired Cyberpunk back up, but I play CoD all the time. Now the shunt mod definitely helped, but this was the way to go. I did not gain very much speed. After some testing, the 2080Ti I have in now just tops out at 2085, no matter the volts it just does these weird bursts of light flashy things in Heaven past that and other tests fail or are wonky. GPU memory speeds set to stock for stability testing BTW. So with the new BIOS I set it to 2085/8000 @ 1.125v. 29°C idle and a max of 52°C extended load. Once at that 50°C mark, it clocks down a bin to 2070. With Xtreme Tuner if you don't check the box next to the GPU VOLT slider, normal features like the binning down for temps and 2D down-clocking still work. I set the voltage using the GPU Volt (Offset %) slider. FPS in CoD is now in the 150-200 range and I shaved a ms off the "GPU Time" counter in game (some Reflex thing). That many fps gained for only 15MHz clocks? Not a chance. So, I flashed the card back to the OEM BIOS and ran some tests with GPU-Z running. First Heaven (1440p all maxed), then Superposition (8k) and there it was. PerfCap Reason: Pwr. Checked the Max Board Power draw and saw 373W. So I was smacking the 380W power limit even with the shunts. Keep in mind that 373W read by the card is actually 606W. You have to take the read value and multiply it by 1.625 (0.008ohm on top of the 0.005ohm). Flashed the GALAX BIOS back on and ran some tests. No Pwr PerCap Reason this time. Now, this is where you have to sit and think about what it is you want. The shunts allow you to use stock BIOS with there still being a chance you hit the power limit while voiding warranty. The XOC style BIOS simply allows for unleashed performance without needing to do mods. There has to be a BIOS like that publicly available for your card however. Those can be slow coming. Since you have an ASUS Strix OC 3090, your chances are a bit better that an XOC BIOS will become available to you. Additionally, you are going to need a serious supply of power. I run my card on it's own dedicated 750W supply. Some leftover mining HP server supply and breakout board I had. With all the limiters removed I saw a Max of 444.8W in GPU-Z. Doing the math on that comes out to 722.8W. Did it actually pull that for a split second? Maybe, but the point is the power draw goes up exponentially.
So, it comes down to personal choice:
Hard mod a card and lose warranty, but gain a good bit of performance and keep the OEM BIOS.
-Or-
Soft mod a card, but lose all power efficiency and possibly other features since XOC BIOS are almost never as nice as the GALAX one.