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For now, the only PCIe 4.0 GPUs come in the form of AMD's 7nm Radeon Instinct MI60 for the data center. AMD released the Radeon VII for gamers based on the same 7nm design, but the company disabled support for PCIe 4.0, saying that desktop GPUs don't need the throughput of PCIe 4.0. At least not yet. That means SSDs will be the first PCIe 4.0 devices to come to market for desktop PCs.
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AMD will be employing some mild product segmentation here to avoid having the Radeon VII cannibalize the MI50 – the Radeon VII does not get PCIe 4.0 support, nor does it get Infinity Link support