We have earlier built a server using the Gigabyte W480M Vision W and a Xeon W-1370P (essentially a variation of the above, but with components that Intel markets for workstations), again with 128GB ECC RAM and two M.2 SSDs, as well as several using an ASUS TUF Gaming B550M-Plus and a Ryzen 5800X, again with 128GB ECC RAM etc. These should all be pretty comparable in CPU power and other capabilities, so the differences we see in practice are interesting.
Overall, the Asus P12R-M/10G-2T was the most expensive of these boards (EUR 360 vs. EUR ~200 for the Gigabyte W480M Vision W and EUR ~150 for the ASUS TUF Gaming B550M-Plus). Ok, it gives us 2 10G Ethernet ports.
But, more important for us, it has only one M.2 port, a 2280 one, while the other boards all have one 2280 and one 22110 one. We put two 22110 SSDs into the Asus P12R-M/10G-2T, so we had to buy two PCIe->M.2 adapters or, on one of the two machines we went for one M.2 and one 2.5" SATA SSD.
The board has only two USB ports at the back, which is pretty marginal if you want to connect keyboard, mouse, and a USB stick for installing an OS.
Asus advertises as one of the key features "Onboard ASUS ASMB10-iKVM with ASPEED AST2600 controller for out-of-band management". But they actually don't deliver that. Instead, you have to buy an add-on module for currently EUR57. The iKVM functionality is not essential for us. We would have liked to experiment with it, but only if it had actually been included with the board. As a result of this omission, the VGA port does not work (this is somewhat relevant for us, because our KVM switches use VGA).
The Xeon E-2388G has a maximum Turbo Frequency of 5.1GHz according to Intel. With the default BIOS settings, we see 4.7GHz for load 1 and 4.6GHz for load 8; at that point the system power consumption exceeds 140W (base 44W), mostly in line with the 95W TDP of the CPU. After a while, the clock rate lowers to about 4.05GHz (for our load) and about 100W power consumption. I expected the machine to continue consuming 140W. I also expected to see the full 5.1GHz as long as there is TDP headroom. For comparison, the Xeon W-1370P on the Gigabyte W480M Vision W actually reaches the 5.2GHz that is advertized for it (using the same cooler).
The BIOS has options for enabling higher turbo modes that we left at their default values; maybe this would have enabled to reach the 5.1GHz. What we would have liked to see in the BIOS (but did not find) is an option for reducing the power limit (we would have liked to buy a lower-power CPU instead, but it was not available at the time).
The BIOS is a classical text-mode AMIBIOS, in contrast to the graphical BIOS on the ASUS TUF Gaming B550M-Plus. Visually, I prefer the text-mode BIOS, but the graphical BIOS has one big advantage: When saving the settings, it tells me what settings are changing with the save, while the text-mode interface does not have that feature.
Idle power consumption is 44W, including a hard disk, compared to 36W on the Gigabyte W480M Vision W (without hard disk), and 48W on the ASUS TUF Gaming B550M-Plus (with hard disk, and with a graphics card for lack of CPU graphics on the Ryzen 5800X), and 22W on a Z170 board with a Core i5-6600K, 16GB RAM, 3 SATA SSDs and an optical drive.
On the positive side, the board has a 2-digit 7-segment LED display at the back which tells about the boot progress (quite useful, because it takes a minute or two until it shows something on the screen through HDMI (checking the 128GB or RAM takes its time).
One advantage that this board has over the ASUS TUF Gaming B550M-Plus is that it uses white markings on the black background, while the Gaming board uses a pretty dark grey on a black background; the latter makes it quite hard to read the markings and thus to assemble the machine.