AMD Radeon RX 7900 XT 24 GB Flagship RDNA 3 "Navi 31" GPU PCB Diagram Leak Shows Triple 8

Sep 10, 2023

An alleged PCB diagram of what seems to be AMD's flagship Radeon RX 7900 XT graphics card making use of the top RDNA 3 Navi 31 GPU has been leaked by Igor's Lab. The graphics card is going to feature a considerable power upgrade over the RDNA 2-based AMD Radeon RX 6900 XT graphics cards.

The PCB diagram leaked by Igor Wallossek is close to the reference design of the AMD Radeon RX 7900 XT graphics card. It was reported that the flagship RDNA 3 Navi 31 GPU will feature two 8-pin connectors but this PCB seems a little different. It could be likely that this is a partner/AIC reference board while AMD itself will be using a different board themselves.

So starting with the details, we first glance over the Navi 31 "RDNA 3" GPU in the middle of the PCB which is stated to feature 7 chiplets (1 GCD + 6 MCDs). The GCD is expected to measure 308mm2 & the MCDs will measure 37.5mm2 each, rounding up to 225mm2 in total package area. That's a 538 mm2 die size in its entirety. Surrounding the MCM GPU are 12 GDDR6 memory modules that can reach up to 24 GB capacities using 16Gb DRAM.

As for the power delivery, the AMD Radeon RX 7900 XT "Navi 31" graphics card is said to feature a 21+3 phase power delivery solution that comprises 16 voltage converters (from 8 phases running in parallel). This alone is a huge upgrade over the 16 phases featured on the Radeon RX 6900 XT & as such, the power requirement has also gone up. Instead of dual 8-pin connectors, this PCB uses triple 8-pin connectors. The card is said to feature a maximum board power or TBP of 450W but the actual figure would be lower than that.

As for display capabilities, the card comes with a single HDMI, and three DP & gets rid of the USB Type-C connector. The full breakdown from Igor is as follows:

via Igor's Lab

AMD has always tried to go a more standardized route with its PCB and cooling designs starting with the RDNA generation and the Radeon RX 7000 series would also be following these pillars. Following is a Radeon RX 6800 XT reference PCB for comparison:

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 SPs or stream processors. This is an increase of 2.4x in cores compared to the 5120 SPs featured on the Navi 21 GPU. The GPU or the Navi 31 GCD is said to measure 308mm2 and will come packaged on TSMC's 5nm process node.

The Navi 31 GPU will also carry 6 MCD's which will feature 16 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.

While this equals 96 MB of Infinity Cache which is lower than the 128 MB featured on the current Navi 21 GPUs, there's also a 3D-Stacked solution in the works which was pointed out recently and that would double the Infinity Cache with 32 MB (16 MB 0-hi + 16 MB 1-hi) capacities for a total of 192 MB of cache. This is a 50% increase versus the current Navi 21 design and it also makes Navi 31 the first GPU with both, chiplet and 3D stacked designs. These chiplets or MCD's will be fabricated on TSMC's 6nm process node and measure 37.5mm2 each.

Yesterday, AMD made a cryptic tweet about how bigger doesn't necessarily mean better. We tried to decipher what that meant in our post here but rest assured, AMD is getting ready for a launch later this year which will tackle NVIDIA's flagship GeForce RTX 4090 graphics cards.