AMD's upcoming Radeon RX 7900 XT design has been dissected by our colleagues from Igor's Lab, who published (sanitized) schematics of the upcoming product. This is set to be one of the best graphics cards when it launches as AMD's flagship RX 7000-series RDNA 3 GPU in the coming months. GPU designers tend to maximize performance on their flagship offerings, which is why modern high-end GPUs are complex, large, power hungry, and require a very sophisticated power delivery subsystem coupled with an advanced cooling system. AMD's new halo part is no exception.
The Radeon RX 7900 XT will use the codenamed Navi 31 GPU based on the RDNA 3 architecture. It will connect to 24GB of GDDR6 memory using a 384-bit interface, with a chiplet design. The GPU is rumored to consist of one graphics chiplet die (GCD) as well as six memory chiplet dies (MCDs) interconnected using AMD's Infinity Fabric. The GCD will be more complex than AMD's current-generation Navi 21 GPU, and deliver substantially more performance. To that end, it will require more power than the existing part.
According to Igor's Lab, AMD's reference Radeon RX 7900 XT will feature three 8-pin auxiliary PCIe power connectors capable of delivering up to 450W of power — plus another 75W from the PCIe slot, though that will likely go largely untapped. This comes from printed circuit board schematic received by Igor, and then "sanitized" to remove any distinctive markings that hint at the manufacturer(s) of the board.
Igor says he has seen multiple board design schematics, and all of them have several things in common. The boards will reportedly use 21 voltage regulator modules (VRMs) that will spread eight 'main' phases across the GPU core, GPU system-on-chip, GPU memory controller, and GDDR6 memory. To some degree, AMD's reference design for the Radeon RX 7900 XT resembles that of the Radeon RX 6900 XT, but it has one extra 8-pin power inputs and is optimized for higher currents and power.
Speaking of auxiliary PCIe power plugs, it is noteworthy that this design uses three 8-pin connectors and not one 12VHPWR (12+4-pin) power connector, which uses the new PCIe 5.0 standard and is set to be used by Nvidia's upcoming flagship solutions. It is unclear whether AMD is sticking to this design on its final boards, but some of its partners with custom PCBs could certainly adopt the latest auxiliary PCIe 5.0 connector.
As far as display outputs are concerned, AMD reportedly plans to install three DisplayPort and one HDMI connector on its reference card, and it will no longer provide a USB-C connector for Virtual Link. It's still unclear whether AMD's upcoming graphics cards will support DisplayPort 2.0 and/or HDMI 2.1 48G. We suspect the answer is "yes," though as with Intel's Arc Alchemist, exact capabilities might be less than the maximum spec.
Since AMD's Radeon RX 7900 XT and other RDNA3-based graphics cards are set to hit the market this fall, makers of add-in-boards are probably finalizing their PCB and cooling system designs for the upcoming products. Igor points out that there might be some changes from the current PCB schematics on final products, but at least we now know that AMD is not afraid of high power consumption for its next-generation flagship graphics product.
It's also entirely possible for AMD to continue to alter specifications at this point. The board designs might be more or less complete, but GPU shader core counts, clock speeds, and memory speeds are all potentially in a state of flux — and pricing "leaks" are basically just guessing at this stage. As with all unofficial information, apply a dash of skepticism, though Igor didn't actually provide any hard numbers on the core specs.
