"The M.2 Socket 3 and SATA Express slot share the same PCIe bandwidth." Does this apply if I only have 1 SATA device on the Sata Express connector?

Hello,

I’d like to buy an NVMe M.2 SSD for dualbooting Linux. I currently have one SSD connected to the SATA port on the right and all of my other SATA ports are occupied as well, so I cannot simply switch ports.

In the manual of my Asus H97-PRO, it says the following (section 3.6.3 only talks about how you can change priorities in the BIOS):

Does this refer only to the small connector on the left, or will my M.2 SSD and my SATA SSD on the right connector actually share bandwidth?

I think that a SATA Express connector is essentially 2 SATA connections + some PCIe lanes (provided by the leftmost connector), and that if I use the SATA Express connector as 2 normal SATA ports, there shouldn’t be any problems since the connector for the PCIe lanes is not in use. If that is the case, I would expect that using an M.2 SSD wouldn’t result in any bandwidth sharing since the PCIe lanes wouldn’t be shared. I found a diagram on Wikipedia, which - if I’m interpreting it correctly - should support the notion that no bandwidth would be shared in this case. I will link to it in the reply, since I’m a new user and cannot put more than 2 images in my post.

Can anyone confirm or refute this?

Thank you! :slight_smile: