Nvidia unveils Pascal specifics — up to 16GB of VRAM, 1TB of bandwidth !!

Nvidia may have unveiled bits and pieces of its Pascal architecture back in March, but the company has shared some additional details at its GTC Japan technology conference. Like AMD’s Fury X, Pascal will move away from GDDR5 and adopt the next-generation HBM2 memory standard, a 16nm FinFET process at TSMC, and up to 16GB of memory. AMD and Nvidia are both expected to adopt HBM2 in 2016, but this will be Nvidia’s first product to use the technology, while AMD has prior experience thanks to the Fury lineup.

HBM vs. HBM2

HBM and HBM2 are based on the same core technology, but HBM2 doubles the effective speed per pin and introduces some new low-level features, as shown below. Memory density is also expected to improve, from 2Gb per DRAM (8Gb per stacked die) to 8Gb per DRAM (32Gb per stacked die).

Nvidia’s quoted 16GB of memory assumes a four-wide configuration and four 8Gb die on top of each other. That’s the same basic configuration that Fury X used, though the higher density DRAM means the hypothetical top-end Pascal will have four times as much memory as the Fury X. We would be surprised, however, if Nvidia pushes that 16GB stack below its top-end consumer card. In our examination of 4GB VRAM limits earlier this year, we found that the vast majority of games do not stress a 4GB VRAM buffer. Of the handful of titles that do use more than 4GB, none were found to exceed the 6GB limit on the GTX 980 Ti while maintaining anything approaching a playable frame rate. Consumers simply don’t have much to worry about on this front.

The other tidbit coming out of GTC Japan is that Nvidia will target 1TB/s of total bandwidth. That’s a huge bandwidth increase — 2x what Fury X offers — and again, it’s a meteoric increase in a short time. Both AMD and Nvidia are claiming that HBM2 and 14/16nm process technology will give them a 2x performance per watt improvement.

Historically, AMD has typically led Nvidia when it comes to adopting new memory technologies. AMD was the only company to adopt GDDR4 and the first manufacturer to use GDDR5 — the Radeon HD 4870 debuted with GDDR5 in June 2008, while Nvidia didn’t push the new standard on high-end cards until Fermi in 2010. AMD has argued that its expertise with HBM made implementing HBM2 easier, and some sites have reported rumors that the company has preferential access to Hynix’s HBM2 supply. Given that Hynix isn’t the only company building HBM2, however, this may or may not translate into any kind of advantage.

HBM2 production roadmap

With Teams Red and Green both moving to HBM2 next year, and both apparently targeting the same bandwidth and memory capacity targets, I suspect that the performance crown next year won’t be decided by the memory subsystem. Games inevitably evolve to take advantage of next-gen hardware, but the 1TB/s capability that Nvidia is talking up won’t be a widespread feature — especially if both companies stick to GDDR5 for entry and midrange products. One of the facets of HBM/HBM2 is that its advantages are more pronounced the more RAM you’re putting on a card and the larger the GPU is. We can bet that AMD and Nvidia will introduce ultra-high end and high-end cards that use HBM2, but midrange cards in the 2-4GB range could stick with GDDR5 for another product cycle.

The big question will be which company can take better advantage of its bandwidth, which architecture exploits it more effectively, and whether AMD can finally deliver a new core architecture that leaps past the incremental improvements that GCN 1.1 and 1.2 offered over the original GCN 1.0 architecture, which is now nearly three years old. Rumors abound on what kind of architecture that will be, but I’m inclined to think it’ll be more an evolution of GCN rather than a wholesale replacement. Both AMD and Nvidia have moved towards evolutionary advance rather than radical architecture swaps, and there’s enough low-hanging fruit in GCN that AMD could substantially improve performance without reinventing the entire wheel.

Neither AMD nor Nvidia have announced a launch date, but we anticipate seeing hardware from both in late Q1 / early Q2 of 2016. http://www.extremetech.com/gaming/218224-nvidia-unveils-pascal-specifics-up-to-16gb-of-vram-1tb-of-bandwidth