Question M.2 to U.2 adapter, but where to plug it in. (CPU-M.2 or chipset-M.2 slot)

The M.2 to U.2 adapter for the secondary drive goes...

  • ... the M.2 slot connected to the CPU.

  • ... the M.2 slot connected to the X570 chipset.

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Oct 13, 2019
G'day everyone!

As mentioned in a previous post, I'm about to build a new PC on the X570 platform for home use, design work (Altium), some light video editing and some occasional gaming.
I have already ordered a Corsair MP600 PCIe 4.0 M.2 1TB SSD which I was going to use as a system drive. I already own a Samsung 2TB SATA SSD for storage, but most of my data is stored in a NAS anyways, so storage capacity is not that important in this build.

On the other hand, there is this little enthusiast inside my head, which is really freaking excited, because he just found out that the "old" SSD my father gave me two years ago (he worked in the server industry and got it for free), isn't a boring SAS drive like I always thought, but rather an SFF-8643 PCIe 3.0 4x NVME drive with crazy fast read-speeds. Of course, you've already guessed it, I want to somehow implement this into my build... Unfortunately, the X570 platform doesn't support U.2 on any board except that one ASUS workstation board, which honestly isn't an option. So I've found out that there are M.2 to U.2 adapters and even PCIe to U.2 cards, so there is a way.


Finally to my question: IF I use the M.2->U.2 adapter solution, what would go into the CPU-M.2 port, and what into the chipset M.2 port? (System NVMe PCIe 4.0 M.2 drive or U.2 adapter with PCIe 3.0 drive?

I tend to put the system drive with PCIe 4.0 into the CPU-M.2, because this drive has the highest priority and I believe that the CPU-M.2 port is faster since it's "closer" to the CPU. Am I wrong?

Thanks for any advice! I'll post a link to the build-log once there is one ;)

Edit: Sorry if I've chosen the wrong sub-forum. Might be storage or mainboard?