Ill start off by saying you should really just get a 3 plug card if your looking to buy.
I was unlucky after having a STRIX ordered then the store canceling my order and giving my the option of a 3090 XC3 and $400 refund or wait 3-5 months so thats what I got.
But anyway here is how I went about making this card not so terriable.

First off getting a base line for this card.
Benchmarks put it about 1-2% better then a high end 3080. (Which you dont want to see when you just spent 1K more then one of those cards and you see the high end 3090 doing 10-15% better)
It was unable to hold its advertised 1725mhz clock since it was just always slamming against 350W power limit.

Theres currently 4 threads on here from others complaining about the same thing, "Low XC3 scores".
The powerlimit is 100% the issue, The only way to fix this is to flash a higher power limited bios.
From my testing the KFA2 390W bios is the best one for the card since its VRM and Fan design matches EVGAs and you dont lose a DP like the Gigabyte Gaming OC 390W bios.
There is also the 1KW EVGA XOC bios. Its a 3 plug bios so the readings you get in software will be wrong by 33%.
(This is why using a 3 plug bios results in less power making the 480 and 520W bios useless)

Here is the data from testing.

Notes: Make sure you set a lower power limit if you decide to go the XOC bios you will also want to set a custom lower power profile to switch to at idle since there is no idle clocks for the vram.
If using the KFA2 bios on 390W youll want to set a custom fan profile. The stock profile has the fans only getting to 75% at 80C if you set a custom profile with them ramping to 100% at 80C then youll end up around 72C.
I was unable to test the XOC bios in competely stock cooling layout since I had already removed the cooler and re-pasted by the time that bios was released.

What you can see from the graphs is performance is tied to power usage and scales very well with more power. Realisticlly we cant expect any offical bios higher then 390W since thats already pushing out of the ATX spec limits, (Even tho Nvidia does 400W with 2X 8pins).
Also the stock cooler isnt as bad as people make out. The fan profile just needs to be a bit more agressive. There are also gains to be had by repasting the card but be aware this will destroy the thermal putty on the inductors and likely rip the thermal pads on the vrm and vram so make sure you have some new ones to go on just incase.

So on to flashing.
IMO this will void your warranty but Forum Mod Sajin has said in other posts as long as you flash back the orignal bios before sending the card back it will still have warranty.
If the card is unable to boot to windows to flash it you can use a external programer like ch341a with 1.8V and SOP-8 clip adapter.
The bios chip can be found between the pci-slot and die and its part number is MX25U8033E.


I have made a tool that lets you extract/embed your own bios into to EVGA update.exe bios flasher so no need to mess with nvflash and command line.
This tool can be found here.
https://github.com/bmgjet/EVGA-Bios-Unpacker

Alternativly here is a 390W update.exe already modded.
https://mega.nz/file/OLhR...LpkO7KiXybdLA7ul6nGJrM
I wont provide the 1KW XOC already modded since that is really a risk to your card if your not careful.

Simply run the exe. It will tell you your going to update your bios and press Y.
Then it will say the boards miss match and do you want to continue press Y again then restart your computer.

Since this is not a bios from EVGA the LED control will stop registering in PercisionX1.
Here is the fix for that.
https://github.com/bmgjet/EVGA-GPUINFO-Editor

You need to edit the GpuInfo.bin file to add the different device id of this bios in place of what you want the card to identify as.
Theres a video sort of showing how this is done here.
https://www.youtube.com/watch?v=6HgMYBYE3RQ
Then you need to replace the Library.dll file since it has a lock out for any cards not matching EVGA device ID. You can find info and download link for that on the same github as the GPUINFO Editor.
And thats it.

Nice write up here. This will definitely be helping out 3090 XC3 owners.

EVGA1225
Thanks for sharing. Seems like the XC3 performs just as well as the Kingpin giving the same power. Maybe the Kingpins aren't binned after all.

From what iv seen mentioned kingpin is "cheery picked" for 2100mhz. But then you also have a few sources have mentioned 90% of chips will do 2100mhz+ given enough power and cooling anyway.
Voltage control and a quality PCB are what your paying for with the kingpin.
Mine probably only has another 50-100W before it reaches the end of the VFR table since its already running 1.05V for 2125mhz. The end of VFR table being 2175mhz on 1.098V then theres nothing more that can be done outside of hardware mods for more voltage. Where kingpin could just change one of the dip switches or use classified tool.

Not that I can run anymore power anyway without risk of blowing the fuses on the XC3 for the 8pin plugs. The kingpin only has 1 fuse for the pci-slot.

Interesting tools & results

This is all useful information.  However, you didn't mention that your 3090 XC Ultra was shunt modded, or how it was shunt modded.  Now you are going to have many 3090 XC Ultra owners switching their bios to KFA2 or XOC but perhaps not getting as good of numbers shown in your chart.  Without shunt modding, would the 1KW EVGA XOC bios be of any benefit over the KFA2?

You don't need protecton.

AARTXCVI
Hello. I successfully flashed my 3090 XC3 Hybrid to the KFA2 Bios. However, for me it did not make too much of a difference so decided to flash back to the original default Bios. I used nvflash to do this and I didn't have any issues flashing back until I tried to enable the --protecton command line, it failes. Any ideas why how to fix this? Should I be worried?

Make a update.exe with your orignal bios in it and run that. That will re-enable the protection since its still broken in NVFlash standalone.

splautz
This is all useful information.  However, you didn't mention that your 3090 XC Ultra was shunt modded, or how it was shunt modded.  Now you are going to have many 3090 XC Ultra owners switching their bios to KFA2 or XOC but perhaps not getting as good of numbers shown in your chart.  Without shunt modding, would the 1KW EVGA XOC bios be of any benefit over the KFA2?

Un-did the shunt mod as soon as 1KW bios came out because its not needed anymore and gives you better pci slot draw on the 1kw bios.
Thats the advantage of using conductive paint to attach them instead of soldering them.

Angilsonart
I have the 3090 xc3 hybrid ultra. Are the steps the same for this card?

Yes thats what my card is.

I would also like to know how to make an update.exe with the original bios.

I was able to get an official statement from Jacob about a new bios for this card, here is what he said : "Unfortunately its the max based on hardware design".
 

@bmgjet thanks for the BIOS, it's working well on my XC3 Ultra, finally can see the PCIE power at full 75W VS ~40W. Good OC as well and very stable with a custom fan curve.  
This is a way better card now than it was prior to the flash. 
 
Question, what games did you use to test your Raster and RTX OC? I want to see if I can push past 100/500 OC, which is what I have at the moment. 

I'm planning to add the hybrid kit to my XC3. Do you know if the KFA2 BIOS will work with it, or would I be forced to use the XOC FTW3 Hybrid BIOS?

Edit: NM, tired brain didn't see that a hybrid was already used with the KFA2.

Also, thought it was worth mentioning that I saw this 1000w BIOS that is supposedly for a 2 plug card.

Doesn't work with NVflash, but might work with your tool...

The 1000W KFA bios wont work with NVFlash it has to be flashed to a blank bios chip with a chip burner and soldered to your PCB.
That bios was made in the bios editing tool I made and some idiot decided to upload it to techpowerup.

Heres the bios editor.
https://mega.nz/file/qa5TwIAS#6-7RjCoTW1jSDF6m-_bYu8PrFi8Jc4UgQ3ayaG21B7o

Double click on the label "Filename" and it will enable editing.
Just youll need a patched nvflash like maxwell had that bypasses the cert checks. Other wise you need to externally program it to a bios chip.

Maybe I'm not reading the charts right....
 
I am a little confused here regarding what can/cannot be accomplished with absolutely no soldering or shunt modifications on the 3090 XC3 Ultra (no mod, liquid metal or physical alterations of any kind on the PCIE resistors or the resistors controlling the pin connectors).
 
With only a BIOS flash.... which BIOS is the highest performing? What performance does that translate to in the chart above?
 
P.S. If I get this card I will likely water cool it (FTW3 cards are not only hard to find, the waterblocks are all sold out), so temps are not a concern....

GlaucomaPredator
I'm not able to get anywhere near the benchmark on Port Roayl with the XC3 ultra. 
I see you are getting about 14K score in PR mine is about 11K, having said this I can only move the power slider to about 111% on the KFA2 390W BIOS. 
And my sweet spot for a manual OC is about 130/500 with custom fan curve, anything more than that has diminishing returns. 
 

Thats like a 3080 score, If your getting that on a 3090 theres something really wrong with your computer.

willynowei
Maybe I'm not reading the charts right....
 
I am a little confused here regarding what can/cannot be accomplished with absolutely no soldering or shunt modifications on the 3090 XC3 Ultra (no mod, liquid metal or physical alterations of any kind on the PCIE resistors or the resistors controlling the pin connectors).
 
With only a BIOS flash.... which BIOS is the highest performing? What performance does that translate to in the chart above?
 
P.S. If I get this card I will likely water cool it (FTW3 cards are not only hard to find, the waterblocks are all sold out), so temps are not a concern....

390W is the most you should run on a completely un-modded card. And even then you will want to turn the fan up a bit higher.
696W is the most youd get using the 1000W bios but you need water cooling to use that.