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New Linux kernel update may have tipped AMD's hand by leaking Big Navi specs

Image via AMD
Image via AMD
A new update to the Radeon Open Compute (ROCm) firmware details some key specs for Big Navi, codenamed Sienna Cichlid, and Navy Flounder. These include the number of Compute Units (CUs) and the memory bandwidth of the two new GPUs from AMD.

Nvidia may have all the headlines with the GeForce RTX 3090 making the rounds in benchmarks, but AMD might swoop in to steal the show next month. Thanks to a sharp-eyed Reddit user, we may have gotten a sneak peek at AMD’s act.

Reddit user u/stblr dug through a recent version of Radeon Open Compute (ROCm), version 3.8, includes firmware for AMD’s upcoming GPUs, codenamed Sienna Cichlid and Navy Flounder. Sienna Cichlid is also known as Navi 21 (or Big Navi), and Navy Flounder denotes either Navi 22 or 23.

The code in the update confirms that Sienna Cichlid (Big Navi) will have 80 CUs and a 256-bit memory bus, while Navy Flounder will have 40 CUs and a 192-bit memory bus.

(The data is listed in the table below. The total number of CUs can be calculated by multiplying the top three numbers for a particular GPU.)

At this stage, it’s difficult to compare Big Navi to the Nvidia RTX 3080, but these numbers give us an idea of how the GPU compares to AMD’s other offerings. For instance, the Radeon RX 5700 XT has the same 40 CUs as Navy Flounder. However, we should note that the RX 5700 XT has a 256-bit memory bus, so Navy Flounder won’t offer a direct apples-to-apples comparison to measure the improvements of RDNA2.

As with all rumors, take this one with a grain of salt. However, considering this data is embedded directly into the firmware for ROCm, there’s a good chance this is legitimate information. Big Navi is rumored to compete directly with the RTX 2080 Ti and come in just below the RTX 3080. We’ll see if its 80 CUs are up to the task when the card officially launches on October 28.

What do you think of the new leak about Big Navi and AMD’s upcoming GPUs? Let us know in the comments.

Parameter Navi 10 Navi 14 Navi 12 Sienna Cichlid Navy Flounder
gc_num_se 2 1 2 4 2
gc_num_cu_per_sh 10 12 10 10 10
gc_num_sh_per_se 2 2 2 2 2
gc_num_rb_per_se 8 8 8 4 4
gc_num_tccs 16 8 16 16 12
gc_num_gprs 1024 1024 1024 1024 1024
gc_num_max_gs_thds 32 32 32 32 32
gc_gs_table_depth 32 32 32 32 32
gc_gsprim_buff_depth 1792 1792 1792 1792 1792
gc_double_offchip_lds_buffer 1024 512 1024 1024 1024
gc_wave_size 32 32 32 32 32
gc_max_waves_per_simd 20 20 20 16 16
gc_lds_size 64 64 64 64 64
num_sc_per_sh 1 1 1 1 1
num_packer_per_sc 2 2 2 4 4
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> Expert Reviews and News on Laptops, Smartphones and Tech Innovations > News > News Archive > Newsarchive 2020 09 > New Linux kernel update may have tipped AMD's hand by leaking Big Navi specs
Sam Medley, 2020-09-23 (Update: 2020-09-25)