X570 and 3x m.2

adrichardson81

adrichardson81

adrichardson81

Associate
Joined
6 Dec 2007
Posts
1,789
Location
Cambridge
Hi all

It looks like the higher end x570 boards have 3 m.2 slots, but the mid-tier boards mostly only have 2 slots.

I know the x370 and x470 boards steal lanes from the 16x or 4x slot to feed their 2nd m.2 slots, but I can't figure if the same thing is happening with the 3 slot x570s. I've looked at the specs, but can't find anything definitive. I'm figuring if they're sharing lanes with the 4x slot, I may as well just use an adapter.

Anyone got any idea how they're set up?
 
adrichardson81 said:
Hi all

It looks like the higher end x570 boards have 3 m.2 slots, but the mid-tier boards mostly only have 2 slots.

I know the x370 and x470 boards steal lanes from the 16x or 4x slot to feed their 2nd m.2 slots, but I can't figure if the same thing is happening with the 3 slot x570s. I've looked at the specs, but can't find anything definitive. I'm figuring if they're sharing lanes with the 4x slot, I may as well just use an adapter.

Anyone got any idea how they're set up?
Click to expand...

All of the flagship X570 boards supply 4x4.0 PCI-e lanes each from the chipset for 2 of the M.2 slots, the 3rd slot gets its lanes direct from the CPU, it doesnt affect any of the other slots on the board.

RyZen 3000 has 24 lanes in the CPU, 4 dedicated to the chipset as before, the 20 are defined by the user, 16 or x8 x8 for the GPU or 2 GPU's, 4 for the nvme drive.

However the chipset now provides 20 full speed PCI-e 4.0 lanes too, hence it generating between 11w and 15w of heat, thats why they added a fan, the same power as a laptop CPU.

Beware though B550 and lower tier boards wont have this, they are still coming with PCI-e 3.0 not 4.0

you can find this info out here in full detail (specifications / details section) https://www.msi.com/Motherboard/MEG-X570-GODLIKE/Specification

AMD® X570 Chipset
  • 6x SATA 6Gb/s ports
  • 3x M.2 slots (Key M)1
    • M2_1 slot (from AMD® X570 Chipset) supports PCIe 4.0 x4 (3rd Gen AMD Ryzen™) or 3.0 x4 (2nd Gen AMD Ryzen™/ Ryzen™ with Radeon™ Vega Graphics and 2nd Gen AMD Ryzen™ with Radeon™ Graphics) and SATA 6Gb/s 2242/ 2260/ 2280/ 22110 storage devices
    • M2_2 slot (from AMD® X570 Chipset) supports PCIe 4.0 x4 (3rd Gen AMD Ryzen™) or 3.0 x4 (2nd Gen AMD Ryzen™/ Ryzen™ with Radeon™ Vega Graphics and 2nd Gen AMD Ryzen™ with Radeon™ Graphics) and SATA 6Gb/s 2242/ 2260/ 2280 storage devices
    • M2_3 slot (from AMD® Processor) supports PCIe 4.0 x4 (3rd Gen AMD Ryzen™) or PCIe 3.0 x4 (2nd Gen AMD Ryzen™/ Ryzen™ with Radeon™ Vega Graphics and 2nd Gen AMD Ryzen™ with Radeon™ Graphics) 2242/ 2260/ 2280/ 22110 storage devices
 
Last edited:
gigabyte the same

Integrated in the CPU (M2A_SOCKET):
  1. 3rd Generation AMD Ryzen™ processors:
    1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 4.0 x4/x2 SSD support)
  2. 2nd Generation AMD Ryzen™ processors/2nd Generation AMD Ryzen™ with Radeon™ Vega Graphics processors/AMD Ryzen™ with Radeon™ Vega Graphics processors:
    1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 3.0 x4/x2 SSD support)
Integrated in the Chipset (M2B_SOCKET/M2C_SOCKET):
  1. 1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe 4.0*/3.0 x4/x2 SSD support) (M2B_SOCKET)
    * For 3rd Generation AMD Ryzen™ processors only.
  2. 1 x M.2 connector (Socket 3, M key, type 2242/2260/2280 SATA and PCIe 4.0*/3.0 x4/x2 SSD support) (M2C_SOCKET)
    * For 3rd Generation AMD Ryzen™ processors only.
  3. 6 x SATA 6Gb/s connectors
  4. Support for RAID 0, RAID 1, and RAID 10
    * Refer to "1-9 Internal Connectors," for the installation notices for the M.2 and SATA connectors.
Click to expand...
 
adrichardson81 said:
Hi all

It looks like the higher end x570 boards have 3 m.2 slots, but the mid-tier boards mostly only have 2 slots.

I know the x370 and x470 boards steal lanes from the 16x or 4x slot to feed their 2nd m.2 slots, but I can't figure if the same thing is happening with the 3 slot x570s. I've looked at the specs, but can't find anything definitive. I'm figuring if they're sharing lanes with the 4x slot, I may as well just use an adapter.

Anyone got any idea how they're set up?
Click to expand...

You'd need to use an adapter to make use of all three at full bandwidth, if they are 4.0 specified drives.

You have a single M.2 with has 4x dedicated lanes from the CPU.
You have a second M.2 which take lanes from the chipset, at either 4x or 2x lanes of PCI-E 4.0
You have a third which, depending on the board layout will normally take the lanes from the chipset as well, in the same 4x/2x lane configurations.

There is no clarity on if when using a 3.0 based drive that the chipset based M.2 slots will allow the full bandwidth on both slot still.
 
Dont know why you would need an adapter, as I said the chipset provides 20 PCI-e 4.0 lanes on its own, (thats not including what the CPU provides) 8 of those are supplied to 2 of the M.2 drives, thats only 8 lanes used up, 12 remaining, 4 I believe are for the bottom PCI slot running at x4 PCI-e 4.0 still 8 lanes left, in total we get 40 PCI-e 4.0 full speed lanes with X570 and RyZen 3000.

the other 3 PCI x 16 slots on that godlike motherboard are x16 x4 x8, buildzoid explains it all here:
 
Thanks all - very helpful! It looks like lane design is flexible enough that you could have 2 4x m.2 with a 4x + a 1x slot without lane sharing.

Reason I mentioned an adapter is that a 4.0 4x slot seems an obvious way of adding another m.2 slot if the mobo only has 2 m.2 slots.
 
The PCH is connected to the CPU with 4 lanes so that's the bottle neck, having 20 lanes on the PCH does not change that unless the PCH somehow bypasses the CPU. I did watch a Youtube video that suggested the x570 would have 8 lanes to the PCH but I dont know if that is true?
 
FredFlint said:
The PCH is connected to the CPU with 4 lanes so that's the bottle neck, having 20 lanes on the PCH does not change that unless the PCH somehow bypasses the CPU. I did watch a Youtube video that suggested the x570 would have 8 lanes to the PCH but I dont know if that is true?
Click to expand...

Looks like it's 4 lanes so definitely a potential bottleneck. That said, I'll be running pcie 3.0 drives anyway for the time being, so it won't be that bad in my use case.
 
adrichardson81 said:
Thanks all - very helpful! It looks like lane design is flexible enough that you could have 2 4x m.2 with a 4x + a 1x slot without lane sharing.

Reason I mentioned an adapter is that a 4.0 4x slot seems an obvious way of adding another m.2 slot if the mobo only has 2 m.2 slots.
Click to expand...

Yes you can do that, not so sure about the x4 slot though as that's still connected to the PCH, in fact the godlike board I linked earlier actually comes with an add in card for a further 2 m.2 drives, effectively you can run 5 m.2 drives on that board, I'd imagine the add in card though will limit your GPU to 8x, the first 3 slots are connected to the CPU, the last x4 slot is to the pch.
 
Jamin280672 said:
Yes you can do that, not so sure about the x4 slot though as that's still connected to the PCH, in fact the godlike board I linked earlier actually comes with an add in card for a further 2 m.2 drives, effectively you can run 5 m.2 drives on that board, I'd imagine the add in card though will limit your GPU to 8x, the first 3 slots are connected to the CPU, the last x4 slot is to the pch.
Click to expand...

Yeah it'll drop down to 8x. That's what I'm doing now and haven't noticed a hit with my 1080, but I'm guessing you might with something more powerful. The big advantage of pcie 4.0 cards is 8x will be more bandwidth than they need for quite some time.
 
remember with 'LANES' your going from PCIe 3.0 to PCIe 4.0 which is double the bandwidth .

seem a lot on other forums and threads mention is only 4 lanes etc ... suck on PCIe 3.0 loop.

those for lanes are equal to 8 PCIe 3.0 lanes ... not bad of it when you think of it that way :D
 
orbitalwalsh said:
remember with 'LANES' your going from PCIe 3.0 to PCIe 4.0 which is double the bandwidth .

seem a lot on other forums and threads mention is only 4 lanes etc ... suck on PCIe 3.0 loop.

those for lanes are equal to 8 PCIe 3.0 lanes ... not bad of it when you think of it that way :D
Click to expand...
Yes gen 4 is a nice bump from last gen but when 4x gen 4 m.2 drives are common the forum will be full of post about lower than expected performance when using 2 or more drives (mainly large drive to drive transfers). In everyday usage its unlikely to be a problem.
 
FredFlint said:
Yes gen 4 is a nice bump from last gen but when 4x gen 4 m.2 drives are common the forum will be full of post about lower than expected performance when using 2 or more drives (mainly large drive to drive transfers). In everyday usage its unlikely to be a problem.
Click to expand...

TBF in everyday usage you're probably not going to see much difference between 4.0 and 3.0 other than for large file transfers.

Hopefully we'll see some good deals on 1tb 3.0 drives come Black Friday...
 
You must log in or register to reply here.
Back
Top Bottom