OK, so  I returned my Gigabyte Eagle OC because it had a reduced hashrate.
Since I couldn't get any other card I was forced getting a Gigabyte Vision OC 3080 (it's for my gaming rig)

It seems that unfortunately this one also has the same problem as the Eagle and Gaming variant. As a matter of fact I think it's the exact same card as the Gaming OC except the design of the cooler.

So don't buy any Gigabyte cards if you plan on using them for mining.

In a week or so I expect to receive EVGA XC3 Ultra cards. Hope I will have better luck with them!