Question Do the M.2 slots for SSDs run off PCI?

JTsyo

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Nov 18, 2007
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So I see there's the M.2 form factor but there's also PCI 3.0 and PCI 4.0 SSDs. When looking at the motherboards, does it state whether the M.2 is PCI 3 or 4?
 

In2Photos

Senior member
Mar 21, 2007
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M.2 are typically SATA or PCIe (but I also believe they can be USB). PCIe drives only have a single notch on the edge connector. PCI 3 vs 4 (and now 5 with Zen 4 on AMD) not only is it motherboard dependent but also CPU dependent so you need to check both.
 

Tech Junky

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Jan 27, 2022
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So I see there's the M.2 form factor but there's also PCI 3.0 and PCI 4.0 SSDs. When looking at the motherboards, does it state whether the M.2 is PCI 3 or 4?
It tells you in the manual for the board. Some do both and others are either one or the other.
 
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igor_kavinski

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Jul 27, 2020
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When looking at the motherboards, does it state whether the M.2 is PCI 3 or 4?

1667261990756.png

You can also check the tech specs on Gigabyte's website for this particular model:


1667262120492.png

First one is connected to the CPU. With a Ryzen 5000 series CPU, it offers PCIe 4.0 speed but with 5000G series and 4000 series, it can only run at PCIe 3.0 speed.

2nd M.2 connector will always run at PCIe 3.0 as that's the best this particular chipset can muster.

If you go with Alder Lake/Raptor Lake/Zen 4, the presence of at least one PCIe 4.0 M.2 slot is almost guaranteed, unless the mobo is a really crappy cheap model.
 
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JTsyo

Lifer
Nov 18, 2007
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View attachment 70135

You can also check the tech specs on Gigabyte's website for this particular model:


View attachment 70137

First one is connected to the CPU. With a Ryzen 5000 series CPU, it offers PCIe 4.0 speed but with 5000G series and 4000 series, it can only run at PCIe 3.0 speed.

2nd M.2 connector will always run at PCIe 3.0 as that's the best this particular chipset can muster.

If you go with Alder Lake/Raptor Lake/Zen 4, the presence of at least one PCIe 4.0 M.2 slot is almost guaranteed, unless the mobo is a really crappy cheap model.
Alright cool. I just wanted to be sure these were still using the M.2 slots and not the PCIe slots.
 

Tech Junky

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1667264865255.png

It's just telling you how fast they can potentially go for data. Generations tell us speed, when you see X1/4/8/16 then that's an indicator of slots. However sometimes they get lazy or you glitch the matrix and it might appear to be a slot when it's not.

There are some stupid controllers though in some cases that only operate at a X2 electrically but need an X4 to work. They limit it to X2 to keep them cool under load by limiting the bandwidth.

The other thing to look at though as some OEM's put the M2 into a SATA only mode for one of the slots to conserve the lanes for other devices.

1667265134836.png
 

Hotrod2go

Senior member
Nov 17, 2021
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There's gen 4.0 M.2 NVME storage slot on low end B560 boards, but of course only with a rocket lake cpu. The 4.0 lanes come from the cpu, so if you put a comet lake on there, then no 4.0 lanes.
 
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Shmee

Memory and Storage, Graphics Cards
Super Moderator
Sep 13, 2008
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In general, no, they run off PCIe. I haven't seen PCI been used for some time.
 

In2Photos

Senior member
Mar 21, 2007
874
792
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M.2 are typically SATA or PCIe (but I also believe they can be USB). PCIe drives only have a single notch on the edge connector. PCI 3 vs 4 (and now 5 with Zen 4 on AMD) not only is it motherboard dependent but also CPU dependent so you need to check both.
Is there something wrong with the information I posted? Trying to figure why it got downvoted.
 

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