But note that M2_1 shares bandwidth PCIEX16(G5)_2. When M.2_1 is enabled, the lower PCIe slot is disabled and the primary slot (PCIEX16(G5)_1) runs at x8 only. With bandwidth the same between 5.0 x8 and 4.0 x16, you won’t lose performance on existing graphics cards. Finally, the x4 slot at the bottom connects through the chipset with PCIe 4.0 x4 lanes available.
Like, who cares if you won't lose performance with current generation cards?!?
Slot is rated at 5.0 x16, and should keep working like that at all times unless I plug a x8, x4, or x1 card into it.
Not only you lose bandwidth on the PRIMARY slot, you also lose the whole other x4 slot, and for what?
Most likely on all the extra USB ports whose enumeration at boot time just slows down the booting process.
Stupid board, idiotic compromises, horrible design.
This here crap is why I stopped buying desktop and switched to workstation mainboards.
And even though ASUS also makes workstation boards and I had X299 board before I had to switch brands because this "gazillion ports" cancer has spread to them as well along with some other weird design decisions.
Take a look at their
Pro WS W790-ACE board for example -- 8x USB 2.0, just... why? Total waste. Also M.2 slots are PCI-e 4.0, not 5.0. Why? You literally have 64 PCI-e 5.0 lanes on even lowest of Xeon CPUs, and if you weren't an idiot and if you haven't slapped 5 PCI-e slots on the board where most won't be accessible because of hefty GPUs but went with just 3 x16 slots instead, you could have had all 3 slots be capable of PCI-e 5.0 x16 simultaneously (total 48 lanes) and remaining 16 lanes would allow for 2x PCI-e 5.0 M.2 slots and 8 lanes to spare for other onboard devices.
It's ok to compromise when you don't have a choice. This isn't compromise, it's "designed for obsolescence".