Choosing an SSD Slot

Hello Mudspike!

I acquired a bargain WD SN850X 1TB M.2 NVME drive this week. My gaming rig has an M.2 SSD installed (a Samsung, but much slower).

I’m less concerned about boot performance, and would like to maximize speed of gaming (DCS, at this point, but I’ll explore more in the future).

I’ve seen references to only one slot being directly connected to the CPU and thus affecting performance. On my motherboard (MSI Z690-A PRO) I see that the primary (factory) M.2 slot is marked CPU, while the spares are marked CHIPSET.

Is this speed concern something that I should factor in?

It is possible that I could clone the existing drive and make the new one the boot AND DCS, and only using the original drive for other future expansion.

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Whether the M.2 slot is serviced by the Chipset or by a similar chip on the CPU should not be noticeable, if they are the same speed.

If both slots support the same PCI version, and both slots can be used in conjunction with other connections you are using (motherboard often have more connections than bandwidth, allowing you to choose to use either a second M2 or 3 more SATA or an additional PCI-E for example) it doesn’t matter where you put the new SSD.

Check the motherboard manual to be sure.

For cloning your old drive to the new one, you’re going to either learn about all the partitions Windows creates and do the error-prone work of moving them using some command line interface (I did it once and deleted a boot partition accidentally)… or pay for disk cloning software.
After cloning it, you can easily expand the C-partition to be bigger and use the whole new drive. Then you can wipe the old one. When you’re sure, absolutely sure, that you can boot off of the new one.


Looking here at the motherboard in the storage section…

…it looks like slot M2_1 for direct CPU is nice to have but unlikely to be noticeable in real world gaming scenarios. Basically it means four dedicated full lanes of bandwidth for that slot, with the other M slots are sharing four lanes via the chipset. A full blown gen4 NVMe using all of its bandwidth wouldn’t get close to saturating things, so this is all a bit academic.

If the old M.2 is gen3 then it’s probably nicer to have the WD Black gen4 on M2_1 I guess, so I personally would be tempted to swap them over when putting in the WD. For the gen4 make sure you have a heatsink or at least have a peek at the temperatures in hwinfo64 or something, the new ones run a bit hotter than old.

For gaming, storage is not so much the primary bottleneck even when loading stuff, often because the CPU does things with the data.


Sure is nice having Mr. Technology looking over our shoulder! Very, very helpful.
Good to see you lurking FF!


Just popped in to see if DCS Normandy 3 map was ready to buy again, but looks like a year too early. :wink: