I just wanted to share my AsRock X570M Pro4 results. I bought it to replace an MSI B450M Mortar (which will go into a second machine with an R5 2600). I also bought a new kit of 4x16GB Crucial Ballistix Sport LT Red 3000C15 RAM from Amazon.de for 299€ and I got an Intel AX200 M.2 card with a separate set of two antennae. The antennae fit perfectly in the already existing IO plate holes (there are three and the AX200 has a third solder point for a MHF socket, but it is not populated and the third hole is used as an external DIY clear CMOS button in my build). You have to enable Wifi and Bluetooth in the BIOS, then it works fine. I mostly bought the wifi because it was 20€ total and I wanted the flexibility if I ever move the (small) PC around or to another house. It is now a more complete package.
I haven't messed with CPU settings on the new board. With the Mortar, the latest ABBA BIOS had 6 cores jumping to 4400 MHz single core clock and all cores being between 4100 and 4275 MHz while loaded. With the AsRock it seems to be a bit slower, especially the single core clock speed. But it isn't really noticeable in day to day usage, since the CPU is more than powerful enough for my current tasks, so I haven't fine tuned PBO or general overclocking, just maxed out all the limits and that's it.
RAM OC is another thing. I bought that 64GB kit because it was a good price and I wanted it maxed. It turned out to be a great overclocker. My previous 2 x 16 GB 3200C18 kit (HyperX, Micron rev E) clocked to 3533C16 on the Mortar with the 3700X. The new 4 x 16 GB 3000C15 kit (Ballistix, Micron rev E) easily clock to 3900C16 with a 1:1 FCLK setting on similar voltages to the Mortar. I haven't really fine tuned the timings, but they aren't the worst I think. I've been using it like this for a couple of weeks and it is stable. Also ran Karhu RAM Test to 8k% as the first test. As always, it is difficult to say how much is down to the CPU memory controller, the board layout (T-Topology) and the RAM ICs themselves. I'm just insanely happy about the results.
Compared to the B450, the addition of PCIe 4.0 is mostly notable, because B450 only has 2.0 from the chipset. So the expansion capabilities of the B450 platform are definitely limited. One of my NVME drives only ran at 2.0 speeds and that disabled the PCIe 2.0 x4 slot. One x1 slot was covered by the GPU anyway so I only had USB and one 2.0 x1 slot open for expansion. The AsRock on the other hand has all 4.0 slots, so even using the two M.2 ones I still have an x4 and an x1 4.0 slot. Once 4.0 cards become available, the x1 could be enough to run a 10Gb ethernet card for example. It has the Wifi/BT option onboard, which is a nice to have (no need for a USB dongle). It has more OC options in the BIOS, but I'm not sure that all of them actually do something and they are duplicated at times and it is a bit hard to tell which ones override the others (AsRock seems to have a "throw everything at the wall and see what sticks" approach, which is fine for total noobs who don't enter the BIOS or those who are a bit more experienced but confusing for newcomers who want to learn). It has more SATA ports (don't care) and more fan / pump headers (nice) than the Mortar. Fan control in the BIOS is also fine, but the hysteresis seems to be too small since they ramp up and down seemingly randomly sometimes even when the system is supposedly idle. I'll have to look into that, yet. The SB fan can be controlled as well (tied to SB temperature probe) and it runs at roughly 2200 RPM for an SB temperature or 56°C for me. I don't hear it over the 120mm Noctua case fans (700 - 900 RPM idle) and the other CPU/GPU cooler fans. M.2 temperatures are also no issue at all, wether under the Armor or not. Intel LAN, ALC1200, VRM's okay. Overall, you can see that it is a board based on the flagship chipset. But it is also a typical AsRock budget board. If there was a B550 with PCIe 3.0 from the chipset and a Mortar like implementation of it, I'd be all over that, as I don't think I'll need 4.0 for the next several years still. As it stands, this is the most advanced mATX board for AM4. If you can live with mITX, there are better boards. I don't have an mITX build and because of it, I like the extra expansion capabilities (and cheaper price) of mATX. I got the X570M Pro4 as a customer return from a reputable e-tailer for a good price (158€ including shipping vs 190€). Without that reduced price, I would have gotten another Mortar (Titanium) for my second build for 80€ to 100€ and been fine with it, not missing anything vital.
If you guys have any questions, let me know and I'll try and answer them.