PCIe lanes
PCIe lanes
You're looking to understand your PCIe connections and capacity. Based on your setup, you have a Ryzen 9 5900X on an ROG Strix x570-E motherboard. The chipset supports 16 PCIe 4.0 lanes, with the GPU using 16 and the main NVMe drive using 4, leaving 8 lanes available. Your total is 36 lanes. You currently have two NVMe SSDs and four SATA SSDs. If you remove the USB expansion card, you'd still have room for more NVMe drives. For the Elgato capture card, ensure your PCIe slots are free; your 8 SATA ports should accommodate the NVMe drives without conflict.
I want to start by noting that the question you've raised might not be the most accurate one. The number of PCIe lanes you're using doesn't really impact performance beyond understanding what devices are connected to the CPU and the chipset, as well as the available bandwidth. It's also not about how many lanes the CPU or chipset has—though there are some exceptions on certain platforms—but rather about the overall setup. The key factor is the motherboard and its wiring. Only the chipset and CPU lane availability matter if the board supports them; they act as a limit, and many boards don't utilize all of them (for example, the Strix X570I lacks sufficient space for the full X570 features). To determine what's left, check the available connectors on your board and compare them with the manual. On that system, the main bandwidth sharing happens in the top two x16 slots—either x16/x0 or x8/x8 depending on usage—and the lower PCIe x16 slot connects to the second x1 slot. If that slot is used, it drops to x2 bandwidth instead of x4. It's a bit unclear but should work. If you need direct CPU access, plug it into the second PCIe slot; otherwise, use the bottom slot and avoid placing USB cards there. The manual will clarify how bandwidth is allocated.