Question Meaning of M.2 PCIe/SATA for Mobo?

Jul 12, 2021
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Hi

I just want to make sure I've got this right...

When you're reading specs lists for Motherboards on computer store websites etc - and it says "M.2 PCIe/SATA ", am I right in thinking that means you will never be able to run a PCIE Nvme at full speed on that particular slot? does it mean that either the Nvme or m.2 SATA that you use on that slot will only ever be half speed (x2) rather than full speed (x4)?

Is there any more to this that I'm missing?

cheers!
 
M.2 is just a hardware specification. It knows nothing about speed, lanes, or which interface to use. That part is handled by the motherboard. So read up on the motherboard you want to use to find out what is available on the M.2 connector.
 

Eximo

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Generally this means that the M.2 is a B+M keyed slot. It can run a SATA based M.2 drive (B) or an NVMe based M.2 drive (M)

Also means that there is generally shared data connections with some of the SATA ports on the board, these will be disabled with an M.2 drive is installed.
 
it says "M.2 PCIe/SATA ",
am I right in thinking that means you will never be able to run a PCIE Nvme at full speed on that particular slot?
No. It doesn't mean that.
does it mean that either the Nvme or m.2 SATA that you use on that slot will only ever be half speed (x2) rather than full speed (x4)?
No. It doesn't mean that either.
It just means - M.2 slot can support both NVME(PCIE) and SATA M.2 drives.

SATA M.2 drives will run at full speed regardless.
NVME M.2 drives will run at speed supported by M.2 slot and drive itself.

M.2 slots can be PCIE 2.0, 3.0 and 4.0 (later we'll have PCIE 5.0 too). Next important is number of PCIE lanes dedicated to M.2 slot. Usually it's 2x or 4x.
Higher PCIE version means more bandwidth. Higher number of PCIE lanes - also more bandwidth.

So if M.2 drive is PCIE 3.0 x4 and M.2 slot is PCIE 3.0 x4, then drive runs at full speed.
If M.2 slot PCIE version is lower than NVME drive PCIE version or M.2 slot has less PCIE lanes than is needed by M.2 drive, then drive doesn't run at full speed.

Sometimes nvme drive can have lower performance characteristics, than supported by M.2 slot. Cheaper NVME drives have that.
Then drive can achieve close to full performance even in lower version/lower bandwidth M.2 slot.
 
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Hi

I just want to make sure I've got this right...

When you're reading specs lists for Motherboards on computer store websites etc - and it says "M.2 PCIe/SATA ", am I right in thinking that means you will never be able to run a PCIE Nvme at full speed on that particular slot? does it mean that either the Nvme or m.2 SATA that you use on that slot will only ever be half speed (x2) rather than full speed (x4)?

Is there any more to this that I'm missing?

cheers!
Post a link to the mobo's your looking at.
 
Jul 12, 2021
132
3
85
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Post a link to the mobo's your looking at.

Take this Motherboard for example... See the images below

It's only this one m.2 slot that is half speed compared to the other 3 x full speed... and it seems like it's usually (or always?) the "shared" slot that also does m.2 SATA...

That's why I'm trying to confirm that as soon as you see a "shared nvme/SATA' slot - that you can assume it is a given that for the PCIE Nvme it will always be half speed?


The other thing I noticed on this one is that instead of saying the PCIE Nvme on that 'shared' slot will only be listed as 2x instead of 4x (I have seen it written like this).... but on this one they just show half the speed on one page, then on the specs page it lists it as being PCIE 3.0 x 4 only rather than the others being full PCIE 4.0 x4. So that's just another way of saying half speed essentially right?

The other complication is I've noticed fairly regular contradictory errors on motherboard websites - on the same single website one page says one thing, then the other spec page says another etc... so makes it hard to know what they really mean? Probably from bad translations?


cheers


2 x images below





 
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Jul 12, 2021
132
3
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Hi Eximo

Generally this means that the M.2 is a B+M keyed slot. It can run a SATA based M.2 drive (B) or an NVMe based M.2 drive (M)
So do B+M slots always run at half the maximum PCIE speed when using a PCIE Nvme in that slot?


Also means that there is generally shared data connections with some of the SATA ports on the board, these will be disabled with an M.2 drive is installed.
I assume this has absolutely no affect to the pcie nvme though?


cheers
 
Jul 12, 2021
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BTW I've heard that even if a motherboard slot doesn't list a certain size nvme (eg 22110) - that you can still usually stick it in anyway and just put a standoff or something under the end to prop it up?

Is this true - and if it is - is there a safer/better way to prop it up considering it'll be sideways vertical?

cheers
 

USAFRet

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BTW I've heard that even if a motherboard slot doesn't list a certain size nvme (eg 22110) - that you can still usually stick it in anyway and just put a standoff or something under the end to prop it up?

Is this true - and if it is - is there a safer/better way to prop it up considering it'll be sideways vertical?

cheers
The majority of current NVMe drives are 2280.
What specific ones are you looking at that are 22110?
 

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