I have a question on the feasibility of a storage setup on x370. Ideally, what I would like to do is have a total of 5 m.2 drives in my system: 1 scratch drive, 2 boot drives (sata), 2 storage drives (nvme). I’d like to accomplish this with an add in card, allowing me to put the boot and storage drives on it, with the scratch disk directly to the motherboard. However, I’m not clear on if this will work.
Questions:
1 - Do sata m.2 drives use pcie lanes if they are mounted using a pcie to m.2 AIC? Or will the chipset simply remove some of the sata ports and allocate them to the AIC?
2 - It’s my understanding that x370 has 16 lanes of pcie3 dedicated straight to the cpu, x4 to the onboard m.2, and then x4 to the chipset, which it can then divide to x8 pcie2. In theory, this would allow my setup to look something like this:
GPU- x8 pcie3
storage - x4 pcie3 x2
scratch - x4 pcie3
boot - x4 pcie2 (or however that would breakdown)
Is my understanding correct? or is this just a mess?
3 - Is mixing the nvme and sata m.2 drives on one AIC going to be a problem, or lead to issues with the bifurcation? Specifically, can 2 of the drives function at pcie3 speeds with the other 2 at pcie2 speeds? Is this motherboard dependent?
4 - Would x570 avoid these issues in any way, as the x16 lanes of pcie4 are able to be broken down into x32 pcie3 lanes?
My motherboard is a GA-AX370 Gaming K7 Rev 1, fwiw.
I know this is a very fringe case, but this is how I would like to do my storage if at all possible, and preferably without having to spring for a x570 board. It seems to me possible, even if the sata m.2 drives require pcie lanes to function, even more so if the chipset moves sata functionality to the pcie slot. However, the bifurcation remains a question. Anyone have any idea on this? Feel free to ask any questions you might have, I know this is a bit confusing.
Pcie 4 isn’t going to help you, lanes are lanes, they’re just faster.
Best bet is to consult the instruction manual for your motherboard, they will describe what the sharing setup looks like and maybe provide a diagram of the layout.
IMHO avoid SATA m.2 drives, they offer no benefits and waste a slot that could service a much faster PCI Express drive.
As I understand from my x470 board, one of the m.2 slots is connected to a switch that also supplies a PCIe slot. Using the m.2 turns off the slot. Using SATA in one or more of the slots disables onboard SATA ports.
If you have invested in SATA m.2 drives already, there’s a 2.5" sled out there that will hold two of them and connect to a SATA cable .
It was my understanding that depending on the functionality of the chipset/device you could then divide those lanes down. Since pcie4 is effectively twice as fast as pcie3, then 16 lanes of 4 is essentially 32 lanes of 3. However, I’ve done some reading since then and it definitely seems that isn’t the case. Thanks for making me look a little harder into that!
My first thought was to look for the diagram in the manual. My board is similar to yours for the m.2 ports, both can run sata, in which case each disables a specific sata port, and one can also run as a x4 pcie, which is direct from the cpu. I dont think that my second m.2 is wired for pcie, I think only the taichi had that for x370. I think what a lot of the x470 boards did was to have the first m.2 direct from cpu, and then also have a second that disables a x4 slot if it’s used.
I’m actually a really big fan of sata m.2, they costs about the same as a typical ssd, but without the hassle of the wires and having to shove the drive somewhere. And in a lot of cases there’s really not an opportunity cost of using them, like in my case since no wiring for pcie connectivity on second port.