The RDNA3 Pack to Be Led by AMD Radeon RX 7900 XTX?

The “XTX” brand extension is apparently returning to AMD’s primary marketing names for its future Radeon RX 7000-series SKUs. The “XTX” designation had previously been reserved by the company for internal use to designate SKUs that utilize every piece of hardware that is built into a specific silicon. The business will debut its chiplets packaging design in the client-graphics market with the RX 7000-series, which also features the company’s next-generation RDNA3 graphics architecture. Although multi-chip module (MCM) GPUs are not new, the next-generation “Navi 31” GPU would mark the first instance of many logic chips being housed on a single package for client GPUs.

The MCM GPUs that AMD has a lot of expertise with are single logic chips that are encased in memory stacks. Multiple logic chips are used in “Navi 31,” which is coupled to standard discrete GDDR6 memory components like any other client GPU.

The rumored Radeon RX 7900 XTX has 12,288 stream processors distributed across two logic tiles containing SIMD components. These tiles are rumored to be built on the TSMC N5 (5 nm EUV) foundry process for the time being. The Display CoreNext (DCN), Video CoreNext (VCN), and GDDR6 memory controllers will be built on separate chiplets that will most likely be built on TSMC N6 (6 nm). The memory interface on the “Navi 31” is 384 bits wide.The logic tiles don’t have their own memory interfaces, so they rely on memory controller tiles shared between the two logic tiles, much like a dual-channel DDR4 memory interface shared between the two 8-core CPU chiplets on a Ryzen 5950X processor.

The RX 7900 XTX has 24 GB of GDDR6 memory spread across a 384-bit memory interface. This memory operates at a rate of 20 Gbps, resulting in a raw memory bandwidth of 960 GB/s. AMD is also expected to deploy large on-die caches, dubbed the Infinity Cache, to help the GPU’s memory subsystem run more smoothly.

The card’s typical board power value of 420 W is the most intriguing aspect of this rumor. Technically, this is comparable to the GeForce RTX 4090’s 450 W typical graphics power value. Since AMD teased the 12+4 pin ATX 12VHPWR power connector with its Radeon RX 7000-series GPUs earlier this year during the launch event of the Ryzen 7000 series desktop processors, speculation has been rife that the reference-design board will likely have up to three conventional 8-pin PCIe power connectors. You’ll need four 8-pin connectors for an RTX 4090 anyway.

The RX 7900 XT is expected to be NVIDIA’s second-best SKU based on the “Navi 31,” with fewer stream processors—likely 10,752. The memory size is reduced to 20 GB, and the memory interface is narrowed to 320 bits, resulting in 800 GB/s of bandwidth at 20 Gbps memory speed. Following the trend of AMD’s second-largest GPU having half the stream processors of the largest (e.g., “Navi 22” having 2,560 versus the 5,120 of the “Navi 21”), the “Navi 32” chip will most likely have one of these 6,144-SP logic tiles, as well as a narrower memory interface.