Quick Answer
A Z790 board provides the GPU with a full PCIe 5.0 x16 link plus a CPU-connected PCIe 5.0 x4 M.2 slot: that is 16 Gen5 lanes for the graphics card and 4 for a Gen5 NVMe drive, sourced directly from the Intel CPU. The Z790 chipset then adds further PCIe 4.0 lanes for extra M.2 slots, SATA and networking over the DMI link.
Where Z790 Gen5 Lanes Originate
On LGA1700, the CPU supplies the high-speed lanes. Z790 routes 16 to the primary x16 slot for the GPU at PCIe 5.0 and 4 to a CPU-connected M.2 for a Gen5 SSD. The chipset's additional Gen4 lanes feed the remaining M.2 slots and SATA. So a Gen5 graphics card and one Gen5 drive both run at full speed without competing.
What It Means For Your Build
Even a high-end card like an RTX 5080 does not saturate a Gen5 x16 link in games, so the benefit is headroom rather than instant frame rates. A Gen5 NVMe (1TB around R2,200-R2,800) loads large worlds quickly, though a good Gen4 drive (1TB R1,400-R1,800) remains better value for most. You do not need a flagship board for Gen5; standard Z790 covers it.
Using The Lanes Wisely
Install your Gen5 NVMe in the CPU-connected slot for full bandwidth, and use chipset-connected Gen4 slots for the wider game library. Check the board's lane-sharing table so adding drives does not unexpectedly disable a SATA port.
FAQ
How many PCIe 5.0 lanes does Z790 give?
The CPU supplies 16 Gen5 lanes to the GPU and 4 to a CPU-connected M.2, for 20 usable Gen5 lanes. The chipset adds further Gen4 connectivity beyond that.
Does my GPU need all 16 Gen5 lanes?
No current card saturates a Gen5 x16 link in games, so the spare bandwidth is future headroom rather than a present-day frame-rate gain.
Where should the Gen5 SSD go?
In the CPU-connected primary M.2 slot, which gives the full PCIe 5.0 x4 link. Chipset slots typically run at Gen4 for the rest of your drives.
Build on a standard Z790 board at Evetech, run a Gen5 NVMe in the CPU-connected M.2 slot, and size the GPU to your target resolution.
