AMD canceled the higher-end RDNA 4 GPUs pretty late into development. The Navi 4C SKU would power the Radeon RX 8900 XTX and the 8900 XT. From previous rumors, we already know that this GPU had a complex chiplet-based design. According to the latest rumors, the RDNA 4 flagship was designed with over 200 Compute Units (100 Dual Compute Units) across three Graphics Compute Dies (chiplets). This translates to ~13000 cores or stream processors, more than twice as much as the RX 7900 XTX.
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The latest Linux patches reveal an RDNA 4 GPU with 9 Shader Engines. On Radeon GPUs, a shader engine comprises a set of compute units (16 or 20), shared L1 cache blocks, primitive units, and rasterizers (RB+). Therefore, each SE is the equivalent of the Graphics Processing Cluster (GPC) found on NVIDIA GPUs. It encompasses SIMD32 (shaders) and fixed-function units like the raster backend.
The RDNA 4 GPU spotted in the Linux patch (via AnandTech forums) consists of 9 shader engines which translates to (at least) 144 compute units and 9216 stream processors (cores). That’s 50% more than the 6 SEs featured on the Navi 31 GPU powering the RX 7900 XTX.
According to members of the AnandTech forum, the Radeon RX 8900 XTX (or at least Navi 4C) was going to pack over 200 compute units or 12800+ cores. These shaders would have been spread across three GCDs (chiplets) in groups of 3 or more Shader Engines, each consisting of ~48 Compute Units.
Navi 44 and 48 are the two RDNA 4 dies still in development. The former is expected to power the RX 8600 XT, while the latter will be used for the RX 8700 XT. These are monolithic designs with two and four shader engines, respectively. The RX 8600 XT is expected to deliver RX 7700 XT/7800 XT-grade performance, while the 8700 XT should be as fast as the 7900 GRE/7900 XT.
The Radeon RX 8800 XT is rumored to be an RDNA 3 (Navi 31) Refresh, on par or higher than the RX 7900 XTX at (allegedly) half the price. AMD may unveil the RDNA 4 architecture alongside the Ryzen 9000 CPUs at Computex this June.
