Question C9Z390-PGW mobo and PEX8747 PCIE switch extra lanes question

[LTC8K6]

Does this actually work well for more lanes? Are these lanes any slower?
What's the catch?

Super Micro lists this board as having these configs:

4 PCI-E 3.0 x16 slots (16/NA/16/NA or 16/NA/8/8 or 8/8/16/NA or 8/8/8/8),
1 PCI-E 3.0 x1

https://www.supermicro.com/products/motherboard/Core/Z390/C9Z390-PGW.cfm

https://docs.broadcom.com/docs-and-...e/1824/PEX8747_Product_Brief_v1-0_20Oct10.pdf

 

[RLGL]

some how I get the idea that there is no free lunch

 

[Insert_Nickname]

What's the catch?

That there is still "only" a x16 connection to the CPU, so all devices connected to the PLX chip have too share bandwidth. It's just "expanded" to 32 lanes, that can be configured in various ways.

However, unless you're running multiple PCIe 3.0 x4 NVMe drives, I doubt you'll ever notice anything. A PLX chip is a fine way to expand connectivity a fair bit, and GPUs don't really -need- more then a 3.0 x8 connection anyway.

 

[LTC8K6]

Review:

https://www.anandtech.com/show/13706/the-supermicro-c9z390-pgw-motherboard-review