Sex Fetish Forum is a large board devoted to the discussion, sharing and enjoyment of pornography. Note that while the forum itself is not entirely devoted to gay porn, there is a section under the 'extreme' area that allows you to share gay sex videos and images.
To date, Sex Fetish Forum has 1.2 million posts in the gay porn forum. While that's relatively average when compared to the other gay boards I've taken a look at, this is exclusively a place for the sharing of fetish pornography. No casual chats, no amateur twinks taking selfies: just hardcore, in your face sex that features gay guys in a world of hurt.
Forum titles range from 'humble sissies slurp cum after anal workout' through to 'best BDSM collection'. I think it's up to you to head on over and find the content that is most relevant to your interests, so go ahead and do that now to see if what Sex Fetish Forum has is your cup of tea.