No, not all x470 boards support PCIe Gen4.
No, not all x470 boards support PCIe Gen4.
I'm curious about whether it's possible to save money and get an x370 paired with a Zen 2 CPU.
Only B450 and X470 models are available. Disappointing with AMD.
Country? Total cost for the project? What are the main purposes? Do you already have components? Are there any spare parts available? X boards seem unnecessary unless you require additional PCIe slots and prefer a B board instead; otherwise, if the X board matches the price and tier, it might be better to stick with it. You probably aren't purchasing new high-end AM4 chips unless you need them, and in that case, consider what boards and CPUs are on the market and their prices. As for PCIe Gen 4, it's irrelevant unless you're using a 6500X or a Gen4 drive—those are mostly irrelevant for gaming.
You require specific PCIe lane configurations. The X470 offers more lanes than the B550, which is why you prefer it over the latter. It makes more sense from a performance standpoint.
PCI-e 4.0 demands higher quality PCBs and improved trace design. You can achieve the signal standards needed by PCI-e 4.0 using additional PCB layers and routing across multiple planes. Interestingly, some x470 motherboards were built with more layers, similar to server boards. x370 models generally performed poorly and aren't recommended today. Even with x470, adding layers increased costs elsewhere—such as VRM quality or older audio chips. There are several B450 boards with superior VRMs compared to x470s, making them more valuable only if you specifically needed to split the 16 into two 8 slots.
There were B450 and X470 boards compatible with PCIe Gen 4. However, AMD insisted that their partners had to provide patches, aiming to keep PCIe Gen 4 exclusive to B550 and X570 models. If you happen to own a board that previously supported Gen 4 and still has a BIOS that allows it, you might be able to use it. These BIOS versions are older than the Ryzen 5000 series, so you can't have both the 5000 series and Gen 4 simultaneously—only Zen 2 (3000 series) offers this combination, but only for the main M.2 and graphics slots. Any additional PCIe or M.2 ports would fall back to Gen 2 or Gen 3. Personally, it’s not worth the effort unless you’re working with high-resolution video editing or handling large files regularly. For most users, Gen 4 isn’t practical beyond specialized tasks. If you really need it, the X570 is the only platform that supports multiple M.2 slots on AM4, while even B550 only has it for the primary slot. If you’re purchasing several Gen 4 drives, upgrading to X570 makes sense even if it’s pricier. Unless you regularly edit high-res video or move massive files, stick with a standard drive and it should suffice.