AMD RDNA 3 Flagship, Navi 31 GPU Rumored To Offer Up To 384-bit Bus & 24 GB GDDR6 Memory, Navi 32 Gets 256-bit For Up To 16 GB Memory


AMD RDNA 3-powered Navi 3x GPUs are now rumored to feature an updated memory layout with the flagship offering the same VRAM as NVIDIA's RTX 4090 graphics card.

AMD RDNA 3 Flagship GPUs Get Upgraded Memory Configuration: Navi 31 Now Rumored To Use 384-bit Bus With Up To 24 GB Memory, Navi 32 Gets 256-bit Bus With Up To 16 GB Memory

The rumor is pretty straightforward and comes once again from Greymon55. There have been recent reports from RedGamingTech that AMD's flagship Navi 31 GPU will be equipped with a bigger 384-bit bus interface compared to the previously speculated 256-bit which was valid but only when the previous specifications were being talked about. It looks like the updated specs lowered the core count but increased the overall memory layout that the flagship RDNA 3 GPUs have to offer.

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AMD RDNA 3 Navi 31 GPUs For Radeon RX 7900 Series

The AMD Navi 31 GPU, the flagship RDNA 3 chip, would power the next-gen enthusiast cards such as the Radeon RX 7900 XT graphics card. We have heard that AMD will drop CU (Compute Units) in favor of WGP (Work Group Processors) on its next-gen RDNA 3 GPUs. Each WGP will house dual CU (Compute Units) but with twice the SIMD32 clusters as opposed to just 2 on each CU within RDNA 2. Rumors are that AMD has the option to select between Samsung and TSMC for the 6nm die.

According to the latest information, the AMD Navi 31 GPU with RDNA 3 architecture is expected to offer a single GCD with 48 WGPs, 12 SAs, and 6 SEs. This will give out a total of 12,288 stream processors which is lower than the previous count. This will also drop the overall compute performance unless AMD goes crazy with over 3.0 GHz clock frequencies on its flagship part. The Navi 31 GPU will also carry 6 MCD's which will feature 64 MB Infinity Cache per die and are also likely to carry the 64-bit (32-bit x 2) memory controllers that will provide the chip with a 384-bit bus interface.

AMD RDNA 3 Navi 3x GPU illustration show possible chip configurations. (Image Credits: Olrak_29)

The Navi 31 (RDNA 3) MCDs will be linked to a single GCD via a next-generation Infinity Fabric interconnect and feature 256-384 MB of Infinity Cache. Considering the latest memory design, next-generation Navi 31 GPUs can be equipped with up to 24 GB of VRAM, the same memory capacity as the upcoming and existing flagship from NVIDIA (RTX 3090 / RTX 4090). The newer memory spec can be seen as a reduction over the previously rumored 32 GB memory but it's definitely going to help tone down the pricing of the card and having parity with NVIDIA while Infinity Cache is in the play can deliver competitive performance in higher-resolution gaming.

AMD RDNA 3 Navi 32 GPUs For Radeon RX 7800 Series

The AMD Navi 32 GPU is also one of the two MCM GPUs featured in the RDNA 3 lineup. The GPU will feature a single GCD (Graphics Compute Dies) and four MCDs (Multi-Cache Die). The die is very similar to the flagship Navi 31 GPU but has one less Shader Engine across each die. The AMD Navi 32 GCD is expected to utilize TSMC's 5nm process node while the MCD will be based on a 6nm process node.

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The GCD will be equipped with 4 Shader Engines and each Shader Engine has 2 Shader Arrays (4 in total). Each Shader Array is composed of 4 WGPs (8 per SE / 32 in total) and each WGP features 8 SIMD32 units with 32 ALUs (32 SIMD32 per SA / 64 per SE / 128 in total). These SIMD32 units combine to make up 8192 cores in total.

The Navi 32 (RDNA 3) MCDs will be linked to the GCD via a next-generation Infinity Fabric interconnect and feature a rumored 256 MB of Infinity Cache. Each MCD should also feature 2 memory connect links (32-bit). That's a total of 8 32-bit memory controllers for a 256-bit bus interface. The graphics chip should provide up to 16 GB GDDR6 memory, the same amount as the existing Navi 21 GPUs but 33% higher memory capacity than the Navi 22 GPUs.

This would bring the performance of the AMD Radeon RX 7700 series above the RX 6800 and RX 6900 series, offering one big leap in graphics horsepower in games. This would also pump up the power numbers as the RX 6700 XT is currently rated at 230W but that could go up to 270-300W.

There have been several rumors stating that the upcoming RDNA 3 GPUs are going to outperform whatever NVIDIA has to offer in terms of rasterization performance and power efficiency. It looks like AMD will take the lead by offering the first MCM-powered GPUs under its Radeon RX 7000 series graphics card lineup.

There are also rumors about 3D Stacking on the flagship Navi 31 GPU and the launch is currently expected in the second half of  2022.

AMD RDNA 3 Navi 3X GPU Configurations (Preliminary)

GPU NameNavi 21Navi 33Navi 32Navi 31Navi 3X
GPU Process7nm6nm5nm/6nm5nm/6nm5nm/6nm
GPU PackageMonolithicMonolithicMCMMCMMCM
Shader Engines42468
GPU WGPs4020-1640-3260-48
SPs Per WGP128256256256256
Compute Units (Per Die) 8040-32160 -128 (Total)240-192 (Total)128 (per GPU)
256 (Total)
Cores (Per Die)51205120-409610240-819215360-122888192
Cores (Total)51205120-409610240-819215360-1228816,384
Memory Bus256-bit128-bit256-bit384-bit384-bit x2?
Memory CapacityUp To 16 GBUp To 8 GBUp To 16 GBUp To 24 GBUp To 32 GB
Infinity Cache128 MB128-256 MB384 MB512 MBTBD
Flagship SKURadeon RX 6900 XTXRadeon RX 7700 XT?Radeon RX 7800 XT?Radeon RX 7900 XT?Radeon Pro
LaunchQ4 2020Q4 2022?Q4 2022?Q4 2022?2023?
Which next-generation GPUs are you looking forward to the most?

News Source: 3DCenter

Products mentioned in this post

RTX 3090
RTX 3090
USD 1639
rx 6800
rx 6800
USD 659.99

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