This is a good scenario to explain the few cards failing to flash. BUT my last search shows that all testimonies about capped GDDR5X start from end of 2017 until now. For instance my 1080 OEM (=FE) was built Q3 2017. Furthermore, my 1080 accepts very good o/c on memory. So I'm not sure it is the right reason.
By the way, the voltage mod didn't work, I tried twice. Coincidence?
I'm OK for flashing a 10Gbps bios, if someone can find one. I already flashed at least 10 different bioses until now.