When it comes to new AMD AM5 motherboards featuring an X670 series chipset, one of the cheapest options right now is the ASRock X670E PG Lightning that retails for around $249 USD.
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ASRock X670E PG Lightning AM5 ATX Motherboard. 4xDDR5 slots, PCIE 5.0X16, AMD Cross Fire, Quad M.2 slots, 2.5GB LAN, 7.1 HD audio, HDMI, DP 1.4 ports, USB3.2 Gen2x2 Type-C, 8 Layer PCB.
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ASRock X670E PG Lightning