ConclusionAt the outset, we offer our profound gratitude to AMD for offering backwards compatibility for its 3rd generation Ryzen processors on motherboards that were designed way back in 2016. Motherboard designers back then would not have anticipated CPU core counts to increase two-fold for a total of 16 cores in just a couple of years, not to mention the added electrical and wiring requirements of the meticulously put together processors. Intel would have surely chickened out on backwards compatibility, as it did by blocking out "Coffee Lake" on its 200-series and 100-series chipset motherboards, including the high-end ones.
It is fairly straightforward to get a 3rd gen Ryzen processor to work on an older AMD X470 motherboard. If you've already been using an older Ryzen processor, simply update your motherboard BIOS, drop in the new processor, and you're good to go. If you bought a new X470 motherboard and a 3rd gen Ryzen processor in one go, don't worry as a majority of X470 motherboards support USB BIOS Flashback, a feature with which you can update the motherboard BIOS even without the processor installed. Your motherboard's manual will tell you how. There are benefits to choosing an X470 motherboard to go with your 3rd gen Ryzen processor right now. PCI-Express gen 4.0 is in its infancy, and the Radeon RX 5700-series graphics cards don't really need it. The swanky new AMD X570 motherboards are expensive, complex, and their chipsets are very hot, requiring a tiny 40 mm fan-heatsink on most motherboards.
The question on your mind will now be whether you lose anything by the way of performance or overclocking headroom. We pulled out an MSI X470 Gaming M7 to find out just that. We are happy to report that you don't lose any performance. When averaged across our test suite that includes 28 tests in a variety of CPU benchmarks that are a mix of real world and synthetics, we find that the X470 platform is negligibly faster (0.18%) for the 3700X and 0.15% slower for the 3900X. The individual tests that post performance gains for the X470 run around 2%–3% faster. The ones that don't are a little over 3% slower. Stock frequency only tells half the story, so we maxed out our Precision Boost Overdrive (PBO) headroom. The net performance loss is 0.23%, with performance swinging between -3 to +2 percent across tests for the 3700X and -2 to +6 for the 3900X, averaging 0.11%. A manual OC of the 3700X to 4.25 GHz also spits out a similar set of variations (within 1 %). We also put the two processors through a small selection of games run across four resolutions (40 game tests per processor in all). The performance variations average under 1% in all three scenarios: stock, PBO max, and manual OC. The story repeats with the 3900X.
The second aspect of your buying decision will be overclocking headroom. AMD revised the CPU VRM and memory wiring specification for its X570 platform to increase CPU and memory overclocking headroom. We managed to get the 3700X to work at 4.225 GHz at 1.28 V and successfully pushed the 3900X up to 4.00 GHz. We achieved the same 4.255 GHz and 4.00 GHz on the ASRock X570 Taichi for the two chips, respectively.
With this data, and the data from our PCIe gen 4.0 scaling article, we are happy to report that you can save yourself anywhere between $70 to $150 by choosing an X470 motherboard over an X570 variant. There are no tangible performance gains to be had as there is no apparent overclocking headroom increase with our review cooling solution and memory kit (which uses Samsung B-die), and certainly nothing is to be gained from PCIe gen 4.0 for now. You even get the added benefit of a motherboard chipset that truly runs Cool & Quiet.