No, the Asus Z790 Hero cannot support two PCIe 4.0 SSDs simultaneously.
No, the Asus Z790 Hero cannot support two PCIe 4.0 SSDs simultaneously.
You're planning to add two Samsung 980pro SSDs to the Asus Z790 Hero motherboard. This setup might affect the PCIe 5.0 bandwidth used by your graphics card. You prefer avoiding the ROG Hyper M.2 card installation. The specs you found suggest compatibility with the ROG MAXIMUS Z790 HERO model, but you need clarity on how many slots are available and their configuration.
Based on my research, the z790 chipset supports up to 4 m.2 slots and does not impact PCIe speeds.
Typically you get four connections and it simply turns off SATA ports without any noticeable effect.
When not using the M.2 expansion card, the GPU will always receive its full bandwidth. Using the M.2 card allows some bandwidth reduction from the GPU if you utilize the second PCIe lane, but placing it in the lower PCIe lane means no reduction occurs. Bandwidth is only taken away if both the second PCIe slot and the bottom PCIe slot are used, which would limit the GPU to its full 16 lanes—no switching is present on this board to reroute lanes to an SSD. The board itself features three M.2 slots, enabling easy installation of multiple Gen 4 SSDs.
On my Z790 tomahawk, running all four M.2 drives causes one SATA port to be disabled.