Worries regarding the i7-10700k with 16 PCIe lanes
Worries regarding the i7-10700k with 16 PCIe lanes
I chose to upgrade from my i7-5820k to the i7-10700k but found only 16 PCIe lanes available. I used the MSI MEG Z490 UNIFY LGA 1200 motherboard. I need two M.2 NVMe drives for my setup. I plan to install a high-end GPU, either from NVIDIA or AMD, based on cost and performance. Could the GPU be affected by the two NVMe drives? Why are the CPU’s PCIe lanes so limited compared to my previous model with 28 lanes? Will even one NVMe drive limit the GPU performance? Thanks!
The CPU lanes connect to the first two PCIe 16x slots in the Unify. The remaining connections are made to the PCH. It's important to verify this beforehand to avoid any possible problems.
The GPU will be removed from the 8x lane if any device occupies the other PCIe x16 port linked to the CPU. The setup specifies three iRST connections (the M2 slots) on the chipset, which turn off SATA and USB ports. Their PCIe lane allocation is tracked under DMI 3.0, not the CPU. The claim of "up to 24 PCIe lanes" refers to the M2 drives using 12 lanes, but the actual DMI bandwidth remains 24 lanes wide (DMI 3.0 x 4). According to the chipset documentation, there are 30 total lanes: 6 dedicated to USB 3.1 Gen 2, with the rest being PCIe lanes or other functions. This is why SATA ports are disabled to free up lanes for PCIe M2 devices—they block the corresponding SATA connections. There are also 10 dedicated PCIe lanes, including 4 in the third PCIe x16 slot, leaving 6 lanes for PCIe x1 and potentially two more if wiring is adjusted. Some boards even disable the single PCIe x1 slots as well.
This situation is quite puzzling. It seems the GPU might drop to x8 even with a single NVME drive, which isn’t what you’d expect. You might want to stick with SATA instead of NVME for simplicity. Regarding the m.2 drives, they use the Z490 chipset’s 24 lanes, not CPU lanes, so they don’t interfere with SATA ports. The confusion about lane counts and port loss comes from different configurations—some sources list only SATA 6 and 5 affected, while others mention all ports. Each column likely represents a lane, but the exact mapping can vary depending on the setup.