CWWK N305 4x2.5GBit - 4x M.2 Expansion Board vs Single PCIe x4 NVMe Drive

[hydrasweetrollspiano]

Hello,

I just received my CWWK N305 that came with the M.2 Expansion Board (CW-ADLN-4PCIE V0.6). I don't need the expansion board as I just want to use a single PCIe Gen4 x4 NVMe drive (Predator GM7000). However, after removing the board and inserting the NVMe drive, it does not recognize it. If I reinstall the expansion board and use the NVMe in the first slot it boots and works fine, allowing me to install Proxmox. However, it only recognizes the drive as having a width of x1.

I saw a very similar post about enabling PCIe Bifurcation that included a response with a screenshot of the PCIe slot selection in the BIOS. What's interesting is that mine was already set to M2 and not CEMx4, but the expansion board was working. I've since tried to boot with the single drive and the setting of M2, as well as CEMx4, but no matter what it does not recognize my NVMe as being installed.

I know the slot works just fine because the drive works just fine when installed in the expansion board, so I feel like it MUST be some setting in the BIOS I'm overlooking. Has anyone had a similar experience or know what (possible setting) I could be missing?

 

[louie1961]

probably need to undo the bifurcation in the BIOS

 

[hydrasweetrollspiano]

probably need to undo the bifurcation in the BIOS

I thought that's what I was doing by changing from M2 to CEMx4 and vice versa under Chipset -> System Agent (SA) Configuration -> PCI Express Configuration -> PCI Express Slot Selection. However, neither setting changes the outcome after reboot. I still get "No NVME Device Found" under Advanced -> NVMe Configuration.

 

[alaricljs]

I recall reading that you need a different BIOS to support the 4x1 adapter rather than direct x4, so I expect you may need a different BIOS. Chat w/ them on their site at cwwk.net to verify and get a DL link.

 

[hydrasweetrollspiano]

I figured it out... sort of. It appears I assumed incorrectly (higher than average outcome) that the Intel i3-N305 chipset supports PCIe Gen4. It does not based on Intel's own specifications. That's what you get for subpar research when real system details are lacking. Nowhere in any description of the device details does it ever mention PCIe generation support. It only specifies lanes available as M.2 NVMe x4.

HOWEVER... I'm now between completely confused and impressed because somehow the M.2 expansion board provided somehow enabled my PCIe Gen4 NVMe to be successfully recognized, and even usable by the system. Not only is the drive recognized by the BIOS, but it is also usable by the processor as I was able to successfully install and boot into a working Proxmox installation. My only guess is that the PCIe interface of the NVMe drive must negotiate with the bus as a Gen3/2/1 device since it's only using x1 PCIe lane. I'd have to dive into the PCIe specification for confirmation, but who has time for that?

I still need to confirm this 100% by trying an older Gen PCIe device, but I'm sure as soon as I insert something Gen3 or older into the main M.2 PCIe slot in place of the expansion board, it will be recognized and work.

 

[alaricljs]

PCIe devices are backwards compatible (hosts are not), so this is probably the BIOS not actually doing the right thing for the M2 setting.