Recently, we have been hearing quite a bit about GDDR5x, with rumours suggesting that Nvidia intends to use it in addition to HBM2 on its Pascal graphics cards next year. Now it would seem that AMD is also planning a similar move, with GDDR5x rumoured to appear on its new 14nm graphics cards next year while we wait for HBM to become more widely available.
Right now, it is believed that AMD has priority access to HBM2, which may already be in fairly limited supply, which means there is still some room left in the market for GDDR5.
According to a presentation by a DRAM maker, which leaked on to the web (Via: Techpowerup), GDDR5x will offer double the data-rate per memory access. GDDR5x is also believed to bring new speeds of up to 12Gbps initially, which is a significant improvement over the 7Gbps we are used to seeing on current GDDR5 chips. The big thing is that GDDR5x will use the same pins as GDDR5, which should make it easy for GPU makers to implement without needing to develop new designs.
From the way things are going, it sounds like GDDR5x will replace GDDR5 for both AMD and Nvidia on lower end graphics cards, while top-end GPUs will feature the more energy efficient HBM2. This is all rumour for now though, we should learn more about AMD and Nvidia's future architecture plans as we move in to 2016.
KitGuru Says: This is a pretty interesting turn. I wasn't really aware of GDDR5x until a few weeks ago and I imagine many were under the assumption that HBM would become more widely adopted next year, though that may only be partially true. At the very least, this move to GDDR5x will put less demand on HBM2 supplies, which means manufacturers will hopefully be able to keep up.