Rumors aside, after AMD’s unexpected preview of their 2013 GPU plans back at the start of this year the company has been mum-as-usual on the matter of their future GPUs. At the time AMD announced that they would have a new GPU microarchitecture by the end of this year, and as 2013 slowly winds down the launch of that new microarchitecture draws near. Normally in these situations we would see AMD continue to stay quiet until they’re ready to fully unveil their products, but with the launch of that new microarchitecture already confirmed, AMD has unexpectedly unveiled a couple of details about one of their forthcoming GPUs in an interview with Forbes.

Interviewing the Corporate VP & GM of AMD’s Graphics Business Unit, Matt Skynner, Matt offered up a couple of basic but important details about AMD’s future plans. First and foremost, AMD’s next enthusiast GPU – already strongly implied to be the launch vehicle for their forthcoming microarchitecture – will be a 28nm product. Explaining why, Matt specifically states that “at 28nm for an enthusiast GPU, we can achieve higher clock speeds and higher absolute performance.” With traditional AMD GPU fab TSMC still ramping up for 20nm anyhow this doesn’t come as a great surprise, but it does put to rest any rumors of a 20nm product launch one way or another.

More interesting perhaps is that Matt also gave Forbes a ballpark number on the die size of their new GPU: GK110 is still 30% bigger than the new GPU, or inverted the new GPU is 23% smaller than GK110. While AMD’s small die strategy has been dead for some time, the company has still shied away from large GPUs for various reasons, their largest GPU since the ill-fated R600 (HD 2900 XT) being the 389mm2 Cayman GPU at the heart of the HD 6900 series. 23% smaller than GK110 would put the die size of AMD’s future GPU at around 425mm2, making it slightly larger than Cayman, or roughly the same size as R600. These are ballpark figures of course, so we’ll know more once the GPU formally launches, including of course how well that large die and new microarchitecture translate into performance.

The full interview can be found over at Forbes. Along with teasing AMD’s next enthusiast GPU, Matt also briefly discusses AMD’s software/driver plans, game bundling, the Radeon HD 7990, and more.