TechPowerUp has discovered that AMD's new RX 7900 GRE features some physically altered properties compared to its bigger RX 7900 series brothers. Even though all three GPUs share the exact same die model, the Navi 31 package found on the 7900 GRE is physically smaller than the one found on the 7900 XT and XTX.
According to an image TechPowerUp (via Expreview) made comparing the 7900 GRE's new package size to Navi 21, AD103, and original Navi 31, the RX 7900 GRE's die packaging has been noticeably altered. The package's outer silver border has been thinned down considerably and reshaped so that the package's physical dimensions look like a square. As a result, the GRE's Navi 31 is closer in size to Navi 21 and is smaller than Nvidia's AD103 that powers the RTX 4080. (The physical size of the GPU die and MCDs remains the same; the only thing that became smaller is the GPU packaging.)
Additionally, the PCB of the RX 7900 GRE is also very different and looks tailor-made specifically for AMD's (currently) China-exclusive RDNA 3 GPU. The biggest differentiator is the number of memory packages installed on the PCB: just eight pads, compared to twelve pads on the RX 7900 XT and XTX.
We suspect that AMD has physically removed the additional piping that was put in place to run the RX 7900 XTX's 384-bit wide memory bus, which would also explain the redesigned PCB. The RX 7900 GRE features a 256-bit wide memory bus, which is significantly narrower compared to the RX 7900 XTX. As a result, removing two MCDs worth of piping is probably how AMD shrunk Navi 31 so much.
What's particularly curious is that AMD's RX 7900 GRE specifications page lists 54 billion transistors for the new chip. The RX 7900 XTX and RX 7900 XT page meanwhile list 58 billion transistors. It could just be a typo, but clearly there's more going on behind the scenes than might otherwise be immediately apparent.
Physically altering a GPU package like AMD has done with the RX 7900 GRE isn't too difficult, but altering the die would be very unusual — that takes a lot of money and time to pull off. We cannot be sure of AMD's exact changes or the reasons for the changes. Regardless, it would be very odd for AMD to go through all this hassle for one SKU that's limited to China.
We expect this revised Navi 31 will show up in some other GPU models down the road, possibly in the RX 7800 series and/or mobile GPU equivalents. Meanwhile, Navi 32 GPUs have not yet shown up.
