NVIDIA RTX 40-series “Ada” GPUs to Stick to PCI-Express Gen 4

NVIDIA’s next-generation GeForce “Ada” graphics architecture may stick to PCI-Express 4.0 as its system bus interface, according to kopite7kimi, a reliable source with NVIDIA leaks. This is unlike Ada’s sister-architecture for compute, “Hopper,” which leverages PCI-Express 5.0 in its AIC form-factor cards, for its shared memory pools and other resource-sharing features similar to CXL. This would make Ada the second graphics architecture from NVIDIA to use PCIe Gen 4, after the current-gen “Ampere.” The previous-gen “Turing” used PCIe Gen 3. PCI-Express 4.0 x16 offers 32 GB/s per-direction bandwidth, and NVIDIA has implemented the Resizable-BAR feature with “Ampere,” which lets the system see the entire dedicated video memory as one addressable block, rather than through tiny 256 MB apertures.

Despite using PCI-Express 4.0 for its host interface, GeForce “Ada” graphics cards are expected to extensively use the ATX 3.0 spec 16-pin power connector that the company debuted with the RTX 3090 Ti, particularly with higher-end GPUs that have typical board power above 225 W. The 16-pin connector is being marketed as a “PCIe Gen 5” generation standard, particularly by PSU manufacturers cashing in on early-adopter demand. All eyes are now on AMD’s RDNA3 graphics architecture, on whether it’s first to market with PCI-Express Gen 5, the way RDNA (RX 5000 series) was with PCIe Gen 4. The decision to stick with PCIe Gen 4 is particularly interesting given that Microsoft DirectStorage may gain use in the coming years, something that is expected to strain the system bus for the GPU, as SSD I/O transfer-rates increase with M.2 PCIe Gen 5 SSDs.