This is the first board I have owned for a long time where all the PCIe slots are non compromises. Using them doesnt disable anything else on the board, just the DMI bus contention.
As an example the second full length slot doesnt slow down the 16x slot to 8x (this seems to be the case on almost every board I have historically owned).
I think compared to my old board I lost a single x1 slot, but I gained an extra full length slot as I can use it without slowing down the 16x.
I spent a lot of time picking out the board, and this I feel was a true gem on Z690. Asus pro art which also seems i/o specialist board was my alternate option.
The slots and i/o on this board (shame it wasnt reviewed by TPU so we got no TPU article to reference).
16x Gen 5 - Populated by GPU.
4x Gen 4 - Available for a Gen 3/4 NVME or other addon card. (This doesnt take lanes from the 16x slot)
4x Gen 3 - Populated by DC P4600 NVME
Two 1x Gen 3 - One populated by sound card. Plan to add network device to another.
8 Intel SATA ports.
1 4x4 M.2 CPU lanes. - Populated by 980 Pro
1 4x4 M.2 Chipset lanes. - Populated by SN850X
1 3x4 M.2 Chipset lanes. - Available for a Gen 3 NVME (out of everything this one does compromise, disables 1 SATA port).
The argument I think is this board did compromise on M.2 to achieve what it did on PCIe, the Taichi e.g. has better M.2 but also not so good PCIe.
If you interested, link to manual is here.
https://download.asrock.com/Manual/Z690 Steel Legend.pdf
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My old Z370, which had primitive M.2 support and multiple compromises. Also only a 1/4 of DMI bandwidth 4x3 lanes compared to 8x4 lanes on Z690.
16x Gen 3
8x Gen 3 (using this reduced first PCIe slot to 8x).
4x Gen 3
Three 1x Gen 3
6 Intel SATA ports
2 Asmedia SATA ports, not suitable for SSDs.
1 3x4 M.2 Chipset lanes. (disabled first 2 Intel SATA ports)
1 3x
2 M.2 Chipset lanes. (disabled last 2 Intel SATA ports)
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If I remember right on Z790 Intel reacted to what the board vendors were doing and swapped 4 PCIe chipset lanes from general allocation to M.2, which had an impact on the Z790 Steel legend (I deliberatly picked the Z690 version for this reason).