AMD Navi 21 ‘Big Navi’ GPU Rumored To Be Featured In 16 GB & 12 GB Radeon RX Gaming Graphics Cards

AMD's Big Navi Radeon RX graphics card rumors are heating up as we get closer to Q4 2020. After the most recent rumor from Chinese PTT forums, a second rumor has emerged which points to a similar story but also adds in an interesting detail about the various configurations that we could expect from AMD's enthusiast-grade RDNA 2 'Navi 2X' GPUs.

The second rumor comes from a more credible leaker 'Wjm47196' from Chiphell who has got many AMD specific rumors correct in the past. According to his latest rumor, the AMD Navi 21 GPU, which is internally referred to as 'Big Navi' and has been spotted with the Sienna Cichlid & Navy Flounder codenames, will feature at least two different memory configurations.

Rogame already pointed out at least four SKUs for the Navi 21 (RDNA 2) GPU but we did not know anything else aside from the PCI IDs. There's active speculation going on right now regarding exact specifications and configurations of each SKU in terms of core counts, texture mapping units, and ROPs since we now know that the GPU consists of 5120 stream processors packed within 80 CUs.

Let's have some fun ????

We know by now that Navi21 die has 80CU. We also know there are 4 variants of Navi21:

Navi21 XTXNavi21 XTNavi21 XL Navi21 XE

W = waterA = Air

How many CUs do you think each variant will have?

I think XE will be cut down memory bus 320bit

— _rogame ???????? (@_rogame) August 5, 2020

As per Rogame, the Navi 21 GPU currently has the following SKUs:

Each GPU SKU will be replacing the existing cards in the Radeon RX 5000 series family but in an entirely different performance segment. For comparison, Navi 10 also has four GPU SKUs that are available to consumers. The Navi 10 XTX chip is the highest binned part which powers the Radeon RX 5700 XT 10th Anniversary Edition followed by the Navi 10 XT GPU that powers the Radeon RX 5700 XT, Navi 10 XL which powers the Radeon RX 5700 and finally, the Navi 10 XLE which powers the Radeon RX 5600 XT.

According to the rumor, AMD is expected to introduce its Big Navi GPU based Radeon RX graphics cards lineup in at least two different VRAM configurations. The flagship variant is said to feature a 16 GB GDDR6 capacity while a cut-down variant is stated to feature 12 GB GDDR6 capacity. A 16 GB VRAM capacity would suggest a 512-bit bus interface for the flagship and a 384-bit bus interface for the cut-down 12 GB model.

Based on the leaked PCI ID for the specific Navi 21 GPU SKUs, we can say that the Navi 21 XTX and Navi 21 XT would come with 16 GB VRAM capacities and a 512-bit bus interface. The XTX variant is essentially a higher-binned variant and there's the possibility that we could see the XTX GPU being water-cooled and the XT variant being air-cooled. That will give users some cooling options as the non-reference (AIB) variants aren't expected later in late December or even Q1 2021.

AMD has kept memory capacities and configurations consistent between the flagship and cut-down variant as seen on Vega 64/56 or the R9 Fury X/Fury cards. What could happen with Navi 21 GPUs is that we could see Navi 21 XTX/XT and Navi 21 XL being 16 GB variants but the Navi 21 XLE variant could be a massively cut down chip with a 12 GB VRAM buffer. We know that the Navi 10 XLE based Radeon RX 5600 XT cut down the memory to 6 GB GDDR6 versus 8 GB GDDR6 on the Radeon RX 5700 series and also offered a reduced 192-bit bus interface vs the full 256-bit bus interface on the Navi 10 XTX/XT/XL parts.

The other possibility is that AMD will only offer 16 GB on the full GPU and tone it down to 12 GB (384-bit) for the cut-down XL variant which might make sense if priced right against the competing NVIDIA Ampere graphics cards. With that said, AMD's Big Navi based Radeon RX graphics cards are expected to launch in Q4 2020 (November) while NVIDIA's Ampere graphics cards will be hitting the retail shelves as early as next month in September.