Best to put M.2 drive in M.2_1 (PCIe5) or M.2_2 (PCIe4)

[NeilF]

Got a ASUS ROG Strix B650E-F Gaming and SPATIUM M480 PRO PCIe 4.0 NVMe M.2 on the way. Should I plug that M.2 into the M.2_1, M.2_2 (or M.2_3 slot)? ie: Will using the primary M.2_1 slot in anyway be counter productive to a PCIe 5 graphics card?

FYI - ASUS ROG Strix B650E-F Gaming:-

• M.2_1 slot (Key M), type 2242/2260/2280(supports PCIe 5.0 x4 mode)
• M.2_2 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 mode)
• M.2_3 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 mode)**
• ** M.2_3 slot shares bandwidth with PCIe 4.0 x16 slot (supports x4 mode) When M.2_3 slot is operating in PCIe mode, M.2_3 will be disabled.

ps: I assume as the M.2 has its own heatsink ditch the motherboard's one?

 

[Tetras]

Will using the primary M.2_1 slot in anyway be counter productive to a PCIe 5 graphics card?

No, AM5 CPUs have spare lanes for the M.2.

ps: I assume as the M.2 has its own heatsink ditch the motherboard's one?

Yeah, it is not usually a good idea to remove them on the ssd.

 

[NeilF]

Thanks... M2_1 it is then

 

[Bobmunkhouse]

Thanks... M2_1 it is then

But why use a pcie5 slot for a pcie4 drive? Won't you just end up having to move it if you get a new pcie5 one?

 

[Bobmunkhouse]

I have this board for new build and planning on using the non pcie5 slots as seems no reason not to....

 

[NeilF]

There's nothing about the PCIe5 slot for M2_1 being a better connection to the CPU than say the PCIe4 M2_2 slot?

EDIT: There does seem to be general talk with Ryzen MBs that M2_1 goes straight to the CPU while the others go through a controller?

 

[Tetras]

There's nothing about the PCIe5 slot for M2_1 being a better connection to the CPU than say the PCIe4 M2_2 slot?

EDIT: There does seem to be general talk with Ryzen MBs that M2_1 goes straight to the CPU while the others go through a controller?

It says in the tech specs and the manual which ones are connected to what, since it depends on the motherboard.

They can have a maximum of 2x CPU connected M.2 slots, but not all boards use both.

But why use a pcie5 slot for a pcie4 drive? Won't you just end up having to move it if you get a new pcie5 one?

I would be less keen on this slot first, because it is under the graphics card.

 

[NeilF]

It says in the tech specs and the manual which ones are connected to what, since it depends on the motherboard.

They can have a maximum of 2x CPU connected M.2 slots, but not all boards use both.


I would be less keen on this slot first, because it is under the graphics card.

There's precious little in the manual. But maybe this (from the manual) implies that M2_1 and M2_2 are in effect the same animal (at least for a PCIe4 M.2 plugged in to them)?

AMD Ryzen 7000 Series Desktop Processors​

• M.2_1 slot (Key M), type 2242/2260/2280(supports PCIe 5.0 x4 mode)
• M.2_2 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 mode

AMD B650 Chipset​

• M.2_3 slot (Key M), type 2242/2260/2280/22110 (supports PCIe 4.0 x4 mode)**
• ** M.2_3 slot shares bandwidth with PCIe 4.0 x16 slot (supports x4 mode) When M.2_3 slot is operating in PCIe mode, M.2_3 will be disabled.

So does that imply a PCI4 M.2 plugged into M2_1 or M2_2 is basically the same?

 

[Tetras]

So does that imply a PCI4 M.2 plugged into M2_1 or M2_2 is basically the same?

Yes, they have used the maximum available CPU lanes for the M.2 slots (many boards don't do this).

Technically, I assume there would be slightly higher latency to the second slot (because it is further away), but this not a meaningful thing to worry about.

 

[NeilF]

So in my case using a PCIe4 M.2, M2_1 and M2_2 are basically the same... In that case - as suggested - if M2_2 is less obscured/covered by the GPU than M2_1, I'll use M2_2.

Thanks...

 

[MissChief]

Always put your primary NVME with your OS into the first slot. 99.9% of the time this will be the one closest to the CPU.

 

[Tetras]

if M2_2 is less obscured/covered by the GPU than M2_1, I'll use M2_2.

The other way around, M.2_1 is usually above the GPU.

 

[NeilF]

The other way around, M.2_1 is usually above the GPU.

Apols... Misread your ealier post. M2_1 it is.

Thanks...

 

[Bobmunkhouse]

Always put your primary NVME with your OS into the first slot. 99.9% of the time this will be the one closest to the CPU.

And what difference will that really make?

 

[Tetras]

And what difference will that really make?

From what I've seen, not a great deal, but they do have lower latency and they don't share the chipset uplink to the CPU, which can be an issue since the 'funnel' is narrower than everything connected to the chipset.

 

[MissChief]

From what I've seen, not a great deal, but they do have lower latency and they don't share the chipset uplink to the CPU, which can be an issue since the 'funnel' is narrower than everything connected to the chipset.

And what difference will that really make?

As Tetras has said, I don't believe it's a massive difference, but the first slot is connected directly to the CPU whereas other slots are generally connected to the chipset and then the CPU and the chipset controller will add a little bit of latency.

 

[Dg834man]

My os nvme gen 3 stared in m_1(gen 4) then got moved to m_2(gen 3) when i bought a nvme gen 4, didn't notice any difference in performance or latency.