M.2 - slot 1 or 2

wizard

wizard

wizard

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Assuming I only want to use one M.2 stick, does it matter which slot (1 or 2) I use? I prefer 2 as it is away from the GPU / CPU for heat purposes.
 
Armageus said:
Depends entirely on the motherboard and the M.2 stick as to what lanes and speeds are available to each slot.

E.g. if you've bought a PCI-E 5.0 nvme drive, then you may find only slot 1 supports those speeds.
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Mine is older ADATA XPG SX8200 Pro 1TB. Currently in slot 2 in my board but wanting to swap board to B550 and wondered about the slot then
 
Check your motherboard manual. There should be a little block diagram of the motherboard and it should show which one uses the PCIe lanes from the CPU you want to use these for a single drive as the slot that uses the chipset PCIe lanes can often be lower performance than the ones from the CPU.
 
mickyflinn said:
B550 boards have 2 x m2 slots , 1 x pcie4 and the other pcie3 so it won't matter which. Usually the top m2 closet to the CPU is pcie4.
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this

(also, slot 1 uses the CPU's PCIE lanes, but slot 2 usually uses the PCH (chipset) lanes...whether this makes a difference to performance though, i'm not sure)
 
tamzzy said:
whether this makes a difference to performance though, i'm not sure
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Afaik, the main issue with chipset lanes is that they're shared between lots of different stuff and everything has to pass through a small uplink to the CPU, so there is added competition for bandwidth and a small increase in latency that doesn't apply to the CPU lanes. That's assuming that everything else is the same, e.g. the same PCI-E gen and have 4 lanes available.
 
Tetras said:
Afaik, the main issue with chipset lanes is that they're shared between lots of different stuff and everything has to pass through a small uplink to the CPU, so there is added competition for bandwidth and a small increase in latency that doesn't apply to the CPU lanes.
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agreed.
what i meant was that i'm not sure if this will show up in real-world usage outside of benchmarks

though...if there's a better cpu-ssd direct connection, i'm not sure why one would use the inferior cpu-pch-ssd connector
heat purposes isn't really a consideration for most ssds outside of PCIE5 drives
 
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Tetras said:
I don't even know if it helps anyway, I've seen some tests where the SSD actually runs cooler underneath the graphics card :o
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If it helps. On my mobo in sig, the M2_1 slot is up next to the ram slots (top-right). My M.2 in there is currently at 25ºC. The other M.2 slots are all located underneath the GPU. In M2_2, my M.2 is at 33ºC. So +8ºC hotter at idle being underneath there.
 
I swapped my pcie 3.0 o/s drive from m.2_1 to m.2_2 when i bought a pcie 4.0 drive for games never noticed any difference in performance, have a b550, but agree with the above use m.2_1 first.
 
From what I understood when I looked into it a few years ago - always use the one closest to the CPU (as it then uses the CPU's PCI lanes rather than the motherboard chipset).

My motherboard, however, had a heatsink included for the furthest one from the CPU so I thought thats the preferred one!
 
All mine have mobo supplied heatsinks.
If I recall correctly both my sys drive and media drive are in the lower m.2 sockets.

I'm far to lazy to change that... Lol.
 
If you read the manual it will list the specs of each slot. If you dont have the manual then it may be available for download from the manufacturers website.

depending on the specs of the slots and specs of the storage drive, it may make no difference but yes it is possible in some cases that it will advantageous to select the best available slot. Especially if you have the newest generation of drives with insane speeds.
 
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