Many mining operating systems recommend setting your GPUs in BIOS to PCIe asic miner GEN 2 as you can see. Perhaps you've already pondered why exactly 2.
The data transfer rate and bandwidth are directly related to the PCIe GEN setting. Cryptocurrency miners typically connect risers using X1 slots on motherboards, and because X1 has unique characteristics for different PCIe settings, these settings can affect the hashrate and performance of your GPUs.
On GEN 2, the maximum speed of the X1 slot is 500 MB/s, which is more suitable for ETH mining.
Buy Pcie Asic miner online
Then there's PCIe GEN 3 and GEN 4, which are currently obsolete until PCIe resize bar support becomes more widespread and not limited to Ryzen motherboards. When this happens, higher GEN settings will allow the 1 GB/s to 2 GB/s to be used.
If you switch to PCIe GEN 3 right now, you won't be able to use as many GPUs because the X1 slot will be given more bandwidth than it requires to operate. Other slots would be unable to load the GPU, or they would consume more power (which would not be visible on the driver's side - i.e. on your minerstat dashboard - because this is the power consumed by the risers and motherboard, not the GPU).