NordicHardware had the opportunity to interview overclocker Mad Tse, who was showcasing the capabilities of custom designed GeForce GTX 1080 HOF at GALAX booth during Computex.
GALAX GTX 1080 HOF: 2.2 GHz on air, 2.5 GHz with LN2
According to Mad Tse, the 8-pin power connector design on reference design is not really a limitation for overclocking. The reference board is using different components than custom designs. MAD points out that reference cards are most likely using locked BIOS. He also mentions that his card was using increased voltage up to 1.3V, which is not possible on reference cards.
While the 2.5 GHz clock he achieved using LN2 cooling is already impressive, it’s not really as important as the clock achieved using air-cooling only. GALAX HOF GTX 1080 is supposedly able to overclock up to 2.2 GHz, without any extreme modifications.
However it is uncertain if NVIDIA approved this card design and its unlocked BIOS, so we don’t know if retail cards will be able to achieve similar frequencies.
Take a look at this interview (the main part is in English):