Instructions on how to update BIOS for a Hybrid Kit conversion is a bit of a gap in the installation instructions and the answer is buried across several threads.  I'm creating this one to hopefully help others who are wondering how they should flash their BIOS to convert an air XC3/FTW3 to a Hybrid, BIOS-wise.  If anyone has any corrections, please by all means let me know and I'll update this post.

1. download the appropriate .zip for your card that Jacob linked in this post
2. shut down, make sure switch is in Normal position, boot
3. flash the Normal bios from the zip, make sure to run as admin / elevated prompt
4. shut down, flip switch to OC position, boot back up
5. flash the OC bios from the zip as admin
6. shut down, leave switch in OC position, boot
7. optionally, for FTWs, flash the HYBRID XOC bios from the sticky thread as admin (3080) (3090)
8. shutdown, boot back up

It now displays 'GeForce RTX 3090 FTW ULTRA HYBRID' and only 2 fans in PX1, like it would with a "real" hybrid.

Hey man thank you for this, really appreciate it. I will be getting my kit soon hopefully as finally snagged one from evga eBay because I live in the AU. Very good write up. Thanks again.

tobincake1471
Instructions on how to update BIOS for a Hybrid Kit conversion is a bit of a gap in the installation instructions and the answer is buried across several threads.  I'm creating this one to hopefully help others who are wondering how they should flash their BIOS to convert an air XC3/FTW3 to a Hybrid, BIOS-wise.  If anyone has any corrections, please by all means let me know and I'll update this post.

1. download the appropriate .zip for your card that
2. shut down, make sure switch is in Normal position, boot
3. flash the Normal bios from the zip, make sure to run as admin / elevated prompt
4. shut down, flip switch to OC position, boot back up
5. flash the OC bios from the zip as admin
6. shut down, leave switch in OC position, boot
7. optionally, for FTWs, flash the HYBRID XOC bios from the sticky thread as admin () ()
8. shutdown, boot back up

It now displays 'GeForce RTX 3090 FTW ULTRA HYBRID' and only 2 fans in PX1, like it would with a "real" hybrid.

common sense

new to this stuff, but trying to do my due diligence. 
 
I tried flashing the Hybrid OC to my system and it says it cannot find any compatible display drivers. The stock and OC bios' flashed just fine... I saw someone saying you need to use NVFLASH to get it to take.. but how do I get the provided files in .ROM? 

Do you really need this for hybrid kit?What's gonna happen if you did not flash this BIOS to your FTW3 Ultra Gaming card?

shiznit
I installed the XC3 Hybrid kit on my 3080 XC3 Ultra. Massive improvement in temperatures, thank you EVGA for continuing to make these affordable kits, so much better than expensive custom loops. I upgrade every generation and I'll continue buying your brand as long as affordable watercooling is available.
 
I started getting hard shutdowns during high GPU load. Is it possible the card wasn't accounting for pump and 2x120mm fan power draw? 8-pin 12v readings were in the 12.1-12.3 range. I'm using a Corsair AX760 Platinum PSU. I flashed the Hybrid bios to see if it would make a difference (couldn't find the BIOS switch to flash the secondary). No hard shutdowns yet but the voltage readings are weird, 12v rails are reading 7.7-9v in HWiNFO64. I tried flashing back to the stock XC3 Ultra bios and it says "No display adapters were found that are compatible with this update."
 
I'm also seeing high idle power consumption, 180-220W. 

Interesting, did the hard shutdown happen before or after installing the Hybrid BIOS?

Also, confirm if the voltage readings are also the same when seeing using GPU-Z instead of HWiNFO...

I edited my original post for clarity, sorry for any confusion.
 
I got the hard shutdowns with the original XC3 Bios, they stopped with the Hybrid XC3 bios. I tried going down to 80% power limit in case it was a some fluke with the pump+rad fan power draw but it still did a hard shutdown.
 
Using the Hybrid bios, the low 8-pin voltage readings and high idle power show up in both GPU-Z and HWiNFO64, I can provide screenshots if you'd like.
 
I just put in the Asus 3070 I was using as a stopgap, the 8-pin voltages and idle power are showing normal.

Thanks for the info. The card is not going into 3D mode. That’s why you are having the low power consumption. Ok, so this may sound unrelated, but could you try to DDU and re-install drivers from scratch?

Otherwise, I would advise to revise all the connections for the hybrid kit and contact tech support.

sendaero
new to this stuff, but trying to do my due diligence. 
 
I tried flashing the Hybrid OC to my system and it says it cannot find any compatible display drivers. The stock and OC bios' flashed just fine... I saw someone saying you need to use NVFLASH to get it to take.. but how do I get the provided files in .ROM? 

I'm not sure about needing to use NVFLASH, I was just able to use the .exe (as admin) and it flashed the XOC bios correctly.  Sorry I couldn't offer anything helpful, other than maybe 2x check that you're running with elevated privileges.

shiznit
It seems the Hybrid XC3 bios is bugged. I flashed the Hybrid FTW bios (with capped power limit to stay within 2x8pin limits) and the voltages look normal:
 
 

Hello, well I can confirm I am in the same boat as you. I flashed the BIOS to the hybrid, then PX1 said they needed to flash BIOS to new version.

Now I am getting the same wrong voltages. Also the card won’t boost past 1950mhz don’t matter how high I boost. Frustrating because I got my card on air to boost to 2040mhz just fine...

Edit: I forgot to add, I did DDU, and re-installed both PX1 and MSI AB. Also ran tests disabling bunch of apps to make sure...

tobincake1471

selarom

shiznit
It seems the Hybrid XC3 bios is bugged. I flashed the Hybrid FTW bios (with capped power limit to stay within 2x8pin limits) and the voltages look normal:

Hello, well I can confirm I am in the same boat as you. I flashed the BIOS to the hybrid, then PX1 said they needed to flash BIOS to new version.

Now I am getting the same wrong voltages. Also the card won’t boost past 1950mhz don’t matter how high I boost. Frustrating because I got my card on air to boost to 2040mhz just fine...

Edit: I forgot to add, I did DDU, and re-installed both PX1 and MSI AB. Also ran tests disabling bunch of apps to make sure...

Just to be sure - only running one at a time, right?  either PX1 or MSI AB?

Yes, only using one at a time.

KhoaBui
Did you flash this BIOS on OC or on Normal mode?

There are two BIOS for the XC3 Ultra? Based on the file linked by Jacob on the other thread, there was only one file. I assumed the normal and OC versions were meant for the FTW3 model and the dual BIOS switches

Ah crap! Really? Wow. Sorry dude.. Mine hasn’t crashed. I was hoping to get my card flashed with the FTW3 BIOS, but I guess .... nevermind

I am also having issues with the 3080 XC3 Ultra Hybrid bios.  I installed the hybrid kit on my XC3 Ultra and flashed the bios using the .exe posted in the link at the top of this forum page, but after flashing, both HWInfo and GPU-Z showed an idle power draw of about 190W just from the GPU.  My AX1200i, however, showed a total system power draw of only 100W while my system was idle.  Clearly, something was off with idle power reading coming from the graphics card.  Moreover, my Timespy, Firestrike, and Port Royal scores were all worse than my stock 3080 XC3 Ultra (temps never broke 50C).  I actually had to undervolt the hybrid card just to get the hybrid's performance to match my stock performance.  I read through this post, and just now flashed back to the XC3 Ultra bios (non-hybrid variant) from Tech PowerUp.  The idle power now reads 38W and my Timespy and Firestrike scores went up by 250+ points each (max temp of 54C).  Flashing back to the stock XC3 Ultra bios seems to have fixed my issues.  Clearly something is amiss with the hybrid bios--at least for cards where a hybrid kit was installed (I can't speak for hybrids bought directly from EVGA).

Thanks for the heads up!  This fixed my problem, and the card now shows up as a proper hybrid.  Just an FYI for anyone else in the same situation.  There are two 3080 XC3 Ultra Hybrid bios files on Tech PowerUp.  The one that fixes the incorrect voltage readout is the bios dated from November (not December).  Both bios files are in the unverified bios section.