*UPDATE*
I've just finished on the phone with EVGA Tech support in regards to my EVGA GeForce GTX 1080 FTW2 DT running BIOS Ver: 86.04.60.00.80 & can confirm (according to the tech at least) the following:
1. There have been no hardware changes within the FTW2 DT lifespan so far, The memory chips are the same across all FTW2 DT e.g 10Ghz
2. The firmware update is only a memory frequency overclock, not a voltage or timing overclock
3. BIOS VER: 86.04.60.00.80 is the latest, My card was manufactured in Dec 2017, the OP firmware updates were for the older firmwares that are not in circulation due to "issues" the tech refused to get into
4. Can confirm that it is ok to downgrade your firmware to the original firmware (Original OP) and then upgrade to the 11ghz firmware (cant confirm if this works)
5. Downgrading & updating your firmware does not void your warranty
7. BIOS VER: 86.04.60.00.80 cannot be updated to run 11Ghz
If anyone has successfully updated their BIOS Ver: 86.04.60.00.8 card to run 11Ghz at stock, let us know! I need your help!