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AMD RDNA 3 GPU Specs: Up To 12,288 ALUs, 96MB Infinity Cache
Although AMD revealed its RDNA 3 architecture in June, the chipmaker refused to share any specifications regarding the next-generation graphics cards. However, Angstronomics(opens in new tab) has shared new information about AMD's newest Navi 3x silicon. The new outlet claims that the specifications were finalized in 2020 and no changes have been made since. Nonetheless, treat the information with some caution.
Angstronomics details three Navi 3x silicon: Navi 31, Navi 32, and Navi 33. Starting from the largest to the smallest, Navi 31 is the flagship silicon and touted as the world's first GPU with a chiplet design. Navi 31, which carries the GFX1100 ID (codename Plum Bonito), reportedly features one Graphics Chiplet Die (GCD) with six accompanying Memory Chiplet Dies (MCD). The publication believes that the GCD is on TSMC’s 5nm process node while the MCD is a product of the 6nm process node.
The GCD, which approximately measures 308 mm², houses up to 48 Workgroup Processors (WGPs). If we break that down, each WGP has two compute units (CUs), meaning that the Navi 31 die sports 96 CUs or 12,288 ALUs. On the other hand, the MCD is around 37.5 mm² in size. Each MCD has 16MB of AMD's Infinity Cache so Navi 31-powered graphics cards will rock up to 96MB of Infinity Cache. Navi 31 comes with a 384-bit memory interface. Navi 31’s Infinity Cache is smaller than Navi 21, which has 128MB of Infinity Cache. Angstronomics reckons that AMD is prepping a 3D-stacked MCD (1-hi) that would double the Infinity Cache. Nonetheless, the performance uplift isn’t substational given the increase in cost so mainstream Navi 31 will stick to 96MB. In fact, a beefed-up version with 288MB Infinity Cache (2-hi) was previously in AMD’s plans, but the chipmaker may have canned it due to the abysmal benefit-cost ratio.
As per Angstronomics' information, AMD may offer a cut-down version of the Navi 31 SKU. The lesser variant may arrive with only 42 WGPs (84 CUs or 10,752 ALUs). The silicon purportedly has one less MCD, maxing out with a 80MB Infinity Cache configuration and a 320-bit memory bus.
Barring any changes, the Navi 31-based reference design seemingly sports an updated triple-fan cooling system that's moderately taller than the existing Navi 21 design. The makeover also includes a three red-stripe accent on the heatsink fins. In terms of power requirement, Navi 31 could do with just two 8-pin PCIe power connectors.
Navi 32, aka GFX1101 (codename Wheat Nas) is the smaller version of Navi 31, targeting both mobile and desktop segments. The GCD and MCD measure 200 mm² and 37.5 mm², respectively. The GCD only has 30 WGPs, amounting up to 60 CUs (7,680 ALUs). The Navi 32 only has four MCDs, limiting the Infinity Cache to 64MB. Once again, it’s less than Navi 22’s 96MB configuration. Angstronomics thinks that AMD contemplated a 128MB (1-hi) variant for Navi 32. The benefit just can’t justify the higher cost So that model may not make it to the market.
On the contrary, Navi 33, GFX1102 (Hotpink Bonefish) sticks to a monolithic design, measuring around 203 mm² in die size. According to Angstronomics‘ report, AMD had planned to make Navi 33 a chiplet die with 18 WGPs with two MCDs. Since the volume and cost didn’t meet AMD’s goals, the chipmaker reportedly stuck with a monolithic die.
We’ll see Navi 33 on both mobile and desktop graphics cards. However, AMD's priority is to push Navi 33 on mobile devices, especially with the AMD Advantage initiative. Therefore, laptops will get priority over their desktop counterparts.
Navi 33 has 16 WGPs, which equals to 32 CUs (4,096 ALUs). Navi 33 boasts drop-in compatibility with Navi 23 PCBs, facilitating adoption among vendors. It has 32MB of Infinity Cache and a 128-bit memory interface. According to Angstronomics, Navi 33 outpeforms Intel's highest-tier Arc Alchemist offering and commands only half the cost of production while also being more power efficient.
AMD will launch the company’s high-end RDNA 3 graphics cards before the end of the year. Nvidia will compete with RDNA 3 with the new GeForce RTX 40-series lineup, rumored to launch in August or September.
