AMD plans on launching a major offensive against NVIDIA with its next-gen Radeon RX 7000 GPUs. Based on the RDNA 3 graphics architecture with as many as seven dies (MCM design), rumors state a performance uplift of 90% over the RDNA 2 flagship. According to Tom from MLID, Navi 31 will lead the charge with up to 512MB of L3 cache and a complex MCM design consisting of 3D stacking similar to the Ryzen 7 5800X3D.
Although the YouTuber expects a sheer raster performance gain of up 130%, considering the past several generations, I’d say we’re not getting anything over the 90-100% mark. In line with previous rumors, the Radeon RX 7900 XT will consist of seven dies: x2 Graphics Compute Dies or GCDs fabbed on TSMC’s 5nm process, x4 Memory Complex Dies or MCDs fabbed on the 6nm node, as well as the I/O die. Tom states that internally at AMD, the 5nm dies are referred to as the GCDs while the 6nm dies as the MCDs. I’m not sure what will be 3D stacked upon what but I’d bet on the MCDs being placed on the GCDs.
It’s unclear whether AMD will go all out with the Infinity Cache and equip the Navi 31 powered RX 7900 XT with 512MB of L3 or a more reasonable 256 MB. The Radeon RX 6900 XT, in comparison, comes with just 128MB of IC. It’s highly probable that the LLC blocks will be paired with the memory controllers across multiple 6nm MCDs. (Ambien) At least, that’s what I expect. Finally, there’s the matter of the TGP. Unlike NVIDIA, AMD is still aiming for a very respectable 450W via two 8-pin or a single 12-pin power connector.
Navi 32 which will power the Radeon RX 7800 XT will also feature a chiplet design albeit with fewer dies. You can expect two GCDs at the very least with two to five MCDs. 3D stacking isn’t confirmed for this SKU but if the layout is the same as Navi 31, you can expect the MCDs to sit atop the GCDs. In terms of performance, picture a 50-70% uplift over the Radeon RX 6800 XT, and a 300-350W TGP.
Both the Radeon RX 7900 XT (Navi 31) and the RX 7800 XT (Navi 32) will feature x16 PCIe gen 5 lanes. The former will launch in the holiday season following the Navi 33-powered RX 7700 XT, and the latter is slated for an early 2023 release.
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