NVIDIA’s next-gen GeForce RTX 40 series “Ada Lovelace” GPUs launch next week, and while we’re hearing a mountain of info on Ada, RDNA 3 isn’t hiding too far away.
AMD’s next-gen RDNA 3-based Radeon RX 7900 XT flagship GPU has been teased, based on the upcoming Navi 31 GPU and now posing for the camera in a new way: a leaked PCB diagram from Igor’s Lab shows off the Radeon RX 7900 XT in all its next-gen GPU glory.
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The new leaked PCB on the Radeon RX 7900 XT shows us what should be very close to the reference design of the RX 7900 XT, where Igor has placed 3 x 8-pin PCIe power connectors on the PCB diagram. With each of the 8-pin connectors capable of 150W, the three here will chew down up to 450W (and 75W from the PCIe 4.0 x16 slot, if AMD uses Gen4).
We can see that beautiful new Navi 31 “RDNA 3” GPU smack bang in the middle of the PCB, made up of 7 chiplets in total (1 x GCD and 6 x MCDs). The GCD is expected to measure in at 308mm2 while the MCDs will measure in at 37.5mm2 each, rounding up to 225mm2 in total package area. That’s a 538 mm2 die size for the entire package.
Around those 7 chiplets, we can find 12 x GDDR6 memory modules, which are capable of taking up to 16Gb DRAM modules for a total of 24GB of GDDR6 memory on AMD’s next-gen Radeon RX 7900 XT graphics card.
AMD is reportedly using a 21+3 phase power delivery system with 16 voltage converters (from 8 phases running in parallel) for its flagship Navi 31-based Radeon RX 7900 XT graphics card. This is a hefty upgrade over the 16 phases that AMD used on the Radeon RX 6900 XT, which is why the power requirements have gone up (3 x 8-pin PCIe power connectors versus 2 x 8-pin PCIe power connectors).
The new Radeon RX 7900 XT is expected to have a maximum board power of 450W but does not need to go anywhere near that (especially in reference Radeon RX 7900 XT form). We should see custom variants of the Radeon RX 7900 XT from the likes of SAPPHIRE, MSI, XFX, PowerColor, and more, pushing that Navi 31 to the limits and testing the 450W maximum board power.
Igor also notes that in the presumed board design, there are 6+2 sockets instead of the 12VHPWR, with Igor noting that he’ll “leave it open whether this PCIe 5.0 connector will make it onto the final cards”. Igor also notes that there are a “total of three tracks on the external PCIe power supply the card’s voltage converters and each of the tracks has an LC combination of coil and upstream polymer caps as output filtering against high-frequency load peaks”.
Igor breaks down his Radeon RX 7900 XT info, with all of the juice below:
- The Navi31 GPU of the RX 7900XT relies on a total of 6 chiplets (I’ll leave the detailed data to the Twitter kings here, but they were quite good lately)
- 12 GDDR6 modules are used, which suggests a memory expansion of up to 24 GB
- There are (besides the usual low and partial voltages) 21 large voltage converters installed in my example, which could be divided as follows if AMD keeps the usual supply scheme: 16 voltage converters (from 8 phases running in parallel) for VDDC_GFX, 2x memory, 2x VDD_SOC and 1x VDDCI. The card would therefore be supplied with 8 phases, which is in line with the general trend (also at NVIDIA). By the way, this is not a speculation, but a real circuit design, but I do not want to go into detail.
- In the left third there are the various voltage transformers for the partial voltages and below the voltage transformer row also the input filtering for the slot (12 volts and 3.3 volts), which I also left out for the reasons already mentioned.
- We recognize 1x HDMI and 3x Displayport, USB-C is not on board
- A total of three tracks on the external PCIe power supply supply the card’s voltage converters and each of the tracks has an LC combination of coil and upstream polymer caps as output filtering against high-frequency load peaks
- In the presumed board design, we see three 6+2 sockets instead of the 12VHPWR. I’ll leave it open whether this PCIe 5.0 connector will make it onto the final cards.
- However, this also limits the maximum board power of the card to 450 watts, whereby the actual TBP should be far below that.