Nvidia RTX 50-Series Flagship Rumored to Offer 512-bit Memory Bus, 28Gb/s GDDR7

We're just a week away from a possible reveal of Nvidia's next-gen architecture, code-named Blackwell. The company is expected to reveal the first details about its follow-up to Ada Lovelace at next week's GTC trade show, which has now been renamed as an "artificial intelligence" conference. Given the proximity of the big reveal, we're starting to get more details about the GeForce version of Blackwell, which is sounding like it'll pack quite a punch, at least regarding its memory subsystem.

The new details confirm some previous reports while contradicting others, so we must keep an open mind regarding these early leaks. The source of these rumors is a typically reliable one, though: kopite7kimi on Twitter, an account known for accurate hardware scoops. In their latest missive, they confirm previous rumors that the flagship Blackwell GB202 die for GeForce will offer a 512-bit memory bus, a big upgrade from the 384-bit memory bus it's offered on all of its recent flagship boards, including the RTX 4090.

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In addition, the account also states that Nvidia will indeed be upgrading the memory subsystem to the new GDDR7 memory standard, which is no surprise. However, unlike previous reports that it would come out of the gate with 32Gb/s modules, now it's being reported they'll be 28Gb/s instead, which is still a decent amount of uplift from the ~21Gb/s memory offered with Ada Lovelace. As Wccftech notes, a GPU with 28Gb/s on a 512-bit memory bus can deliver almost 1.8TB/s of memory bandwidth, compared with around 1TB/s on the existing RTX 4090. Those numbers are about what we expect in terms of uplift in general for the next flagship, which is around 1.7x.

At the same time, the cut-down GB203 die will be roughly half the size of GB202, similar to what Nvidia did this generation with AD102 for the 4090 and AD103 for the 4080 series. Those cards will likely get either a 384-bit or 256-bit memory bus, so we're likely to see once again a vast gulf in performance from the second step of the podium to the top step.

This is the second time this account has mentioned the 50-series flagship offering a 512-bit memory bus, as it was first discussed in September 2023. Since then, more than six months have passed, so perhaps this roadmap has solidified somewhat. We also know that GDDR7 modules are just now making their way to companies like Nvidia and AMD for validation, so maybe the source of these rumors already exists in a lab somewhere.