First, thank you so much for creating this tool! I have a 3090 FTW3 that PX1 gave me no other option than to upgrade the firmware. Though everything appeared to be fine, I quickly found out it wasn't. The rear fan stopped spinning and the LEDs would stutter. Also, the 4 power LEDs would intermittently blink. PX1 would only show two fans, and ICX would only show the core GPU temp, all the sensors were missing. The card still worked display wise, but power LEDs flashing and questionable cooling curves, I was concerned. EVGA tried to troubleshoot the problem, but nothing fixed it.
The card is used extensively for some critical (COVID related) M/L work, so I did an advanced RMA and received a new card. For the new card, PX1 wanted to upgrade the firmware as well, but I decided that I would perform the upgrade on a different machine with nothing installed except PX1.
That PX1 upgrade worked fine and I transferred the card into my original machine and it has worked flawlessly. Knowing that I had a working card, I decided I could take some risks with the card that was going to be shipped back to EVGA anyway to see if I could fix it. Putting the card in the "clean" machine, it still exhibited the same problem, stuttering LEDs and intermittently blinking red power LEDs. After doing some research that pointed to the MCU firmware being the problem. I came across the MCU Tool and figured it I would re-flash, or try to downgrade to see if that addressed the problem. No luck, the firmware upgrade failed about a quarter of the way through. I tried this several times with different downgrades of the firmware using the MCU Tool as well as the current version of the MCU firmware and no luck. My thinking was perhaps I could "force" a MCU firmware write figuring that the initial PX1 attempt somehow got screwed up.
One thing I did notice is that if I shut off all the power to the computer for about 10 minutes or so, that upon reboot, the LEDs would occasionally operate normally but at some point the issues would return. It was after one of these complete power downs that I tried the tool and successfully got it to re-flash the MCU. Now, the card works again, all fans run under load, LEDs work properly and can be configured, all sensors show up in ICX irrespective of which computer the card is placed in or power cycles.
It appears that there are instances where the PX1 MCU flash process is corrupted or incomplete. Using the MCU Tool and re-flash the firmware worked in my case. I've seen several posts that describe the exact same behavior and people having to RMA cards. If this is a fix, EVGA should offer it since it will save time, money, and frustration! Thank you again for the utility, hopefully others that have had the same issue hear about it, use it, and have the same results!