Fresh rumours claim Nvidia's next-gen Blackwell cards won't have a wider memory bus or more VRAM—apart from the RTX 5090

pcgamer.com:

Nvidia's keynote speech at Computex 2024 contained nothing about its next generation of GeForce graphics cards. So, for the time being, we're left to browse through the usual sources of leaks and rumours to build a picture of what's coming. The latest of which suggests that the RTX 5090 will be using a 512-bit wide memory bus, but the rest will be the same as in the current RTX 40-series.

The source of said rumour is Kopite7kimi on X, who has a pretty good reputation for making accurate predictions and statements about future developments in GPUs. In a recent post, the leaker set down the memory configurations for the five Blackwell GPU variants expected to be launched later this year (though some of them may not be announced until 2025).

First up is the GB202, which will undoubtedly be used in the RTX 5090 and a raft of professional-grade graphics cards. The biggest GPUs always have the widest memory bus, so that all those shaders can be kept busy with data—and in the case of the Blackwell monster, it's being claimed that it will sport a 512-bit wide memory bus and GDDR7 VRAM chips.

If one paired that with Micron's slowest GDDR7 chips, which run at 28 MT/s, you're looking at an aggregate bandwidth of 1.8 TB/s or so—roughly 77% more bandwidth than the RTX 4090. Even if the RTX 5090 'only' sports a 384-bit bus, it would still have 33% more bandwidth thanks to the use of faster GDDR7 (the RTX 4090 uses 21 MT/s GDDR6X).

Kopite7kimi suggests the other GPU variants remain unchanged concerning the memory bus width, though. The GB203 is 256-bits, the GB205 is 192-bits, and the bottom-end GB206 and GB207 are both 128-bits. That's the same as the AD103, AD104, AD106, and AD107. However, the use of GDDR7 across most of the graphics cards that will use these GPUs should see a considerable uplift in bandwidth.

GB202 12*8 512-bit GDDR7GB203 7*6 256-bit GDDR7GB205 5*5 192-bit GDDR7GB206 3*6 128-bit GDDR7GB207 2*5 128-bit GDDR6June 11, 2024

It's worth noting that the width of a