Where did the extra 4 billion transistors go?
TechPowerUp has found AMD’s new RX 7900 GRE to feature some physically altered characteristics compared to its larger RX 7900 series siblings.
The Navi 31 package seen on the 7900 GRE is physically smaller than that seen on the 7900 XT and XTX even though the three GPUs share exactly the same die model.
The RX 7900 GRE’s die package has clearly changed, according to images by TechPowerUp (via Expreview) comparing the 7900 GRE’s new package size to the Navi 21, AD103, and the original Navi 31.
The outer silver border of the package has been significantly thinned and reshaped so that the physical dimensions of the package appear to be square.
As a result, GRE’s Navi 31 is closer in size to the Navi 21 and smaller than Nvidia’s AD103, which powers the RTX 4080. (The physical size of the GPU die and MCD remains the same, only the GPU package is smaller).
Additionally, the RX 7900 GRE’s PCB is also very different, appearing to be made specifically for AMD’s (currently) China-only GPU, the RDNA 3.
The biggest difference is the number of memory packages on the PCB, which is only 8 compared to 12 pads on the RX 7900 XT and XTX.
AMD is believed to have physically removed the piping added to run the RX 7900 XTX’s 384-bit wide memory bus, which also explains the redesigned PCB.
The RX 7900 GRE’s memory bus is 256 bits wide, which is considerably narrower than the RX 7900 XTX.
As a result, the removal of 2 MCD’s worth of piping is probably why AMD has shrunk the Navi 31 so much.
What’s particularly strange is that AMD’s RX 7900 GRE specs page lists 54 billion transistors in the new chip. On the other hand, the RX 7900 XTX and RX 7900 XT pages list 58 billion transistors. It’s possible it’s just a typo, but there’s more going on behind the scenes than is immediately apparent.
Physically changing the GPU package like AMD did with the RX 7900 GRE wouldn’t be too difficult, but changing the die would be very unusual and cost a lot of money and time to get it done. It takes
We can’t confirm AMD’s exact changes or why.
Either way, it’s very strange that AMD would go through such a hassle for one China-exclusive SKU.
We expect this modified Navi 31 to appear on other GPU models down the road, possibly the RX 7800 series and/or mobile GPU equivalents.
Meanwhile, the Navi 32 GPU has yet to appear.
sauce:Tom’s Hardware – AMD Shrank Navi 31 in RX 7900 GRE, Smaller Than 7900 XT and XTX
Commentary:
Radeon RX7900GRE Navi31 Die Shrinks Than RX7900XTX/XT
in the article
(currently) for RDNA 3, a Chinese-only GPU
As you can see, it’s already sold in Germany, and I don’t know if it will become a regular model, but it’s certain that it will be rolled out globally, not just in China.
From the name, it may have been for China only.
It’s a little surprising that the RX7900GRE’s GPU die is physically changed.
I’m interested in how much the performance is different from the RX7800/XT, which is probably supposed to have the same amount of memory.
It seems that both AMD and nVIDIA are having a hard time clearing out their inventory of Ampere and RDNA2, but I don’t think they’ll be able to clear their inventory unless they take the plunge or sell them with bundled software.
RDNA3 has finally been able to demonstrate its original performance with recent driver updates, but I would like to see the latest version of FSR3 and ROCm released as soon as possible.
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