[SOLVED] Which M2 Slot?

[12pak]

So I had to change my order for the Z790-A Prime to a ROG Strix Z790-E. In reading about this Z790-E board, I saw one article that recommends using the #2 slot M2 slot instead of the #1 slot that sits right under the CPU because, the article in question says by using the slot next to the CPU, it reduces the lanes that are used by the #1 PCI-e slot, whereas, if you use the #2 M2 slot, it does NOT split the lanes with the PCI-e slot. In looking at the heat sinks of the M2 slots, the #1 slot has the more robust looking heat sink, and it's the only 5.0 slot (which I know is useless right now).

Now call me crazy, but it seems kind of counterproductive to have the main M2 slot share bandwidth with the main PCI-e slot, and at the same time make that the ONLY 5.0 slot, and have the better cooling heat sink. Unless I am misunderstanding what I have read, it would be foolish to use the #1 slot instead of the #2 slot, correct?

 

[Eximo]

That is what they did, but that is splitting the graphics x16 slot PCIe lanes (which are 5.0 capable). Unless you are prioritizing storage over graphics, you should leave that slot empty.

There is still a dedicated 4.0 x4 slot coming off the CPU and not through the chipset.

 

[iTRiP]

Correct, not all motherboards do that though, It'd be though if one couldn't ever find some that actually don't have limitations.

I think I might have run into a limitation upgrading my pc along the way, but its not related.

 

[Math Geek]

if your gpu needs all 16 pcie 5 lanes. then leave that first m.2 slot empty.

if you don't need em all, then use it for the 5.0 storage.

considering 5.0 storage is expensive and brings almost nothing to the table in real world use, it is not worth the expense anyway.

what gpu do you have that actually needs all the 5.0 lanes?? or at least that you think needs all the lanes

 

[Eximo]

Heck, I have an unusable m.2 slot on my board. Only works with an 11th gen chip, when they added the 4x dedicated lanes.

 

[12pak]

So it appears the consensus is the #2 slot would be better and leave the #1 slot empty. 10/4 and thanks for the replies

 

[12pak]

if your gpu needs all 16 pcie 5 lanes. then leave that first m.2 slot empty.

if you don't need em all, then use it for the 5.0 storage.

considering 5.0 storage is expensive and brings almost nothing to the table in real world use, it is not worth the expense anyway.

what gpu do you have that actually needs all the 5.0 lanes?? or at least that you think needs all the lanes

I have no idea if the GPU needs all lanes or not. I've got a Zotac Trinity OC 12GB RTX-3080. I don't intend to buy another GPU for a long time. I will probably need a whole new system by the time I ever buy a 5.0 GPU. Wasn't even really considering how many lanes the GPU actually needs. Was just trying to narrow down the best M2 slot to use for the drive.

 

[Math Geek]

you won't need all 16 lanes anyway for that gpu. so you could actually put it in the first if you feel the need.

but unless you already have a 5.0 ssd, i'd not waste the money nor the effort

so "best" slot is really either one since you'll get full 4.0 ssd speed out of either one and your gpu won't know the difference running at 5.0 x8 (which is actually 4.0 x 16 anyway)

 

[Eximo]

The GPU isn't capable of running at 5.0, so it would be x8 at 4.0. It would cut the bandwidth in half.

Basically what I am doing, running a 3080Ti on a PCIe 3.0 x16 slot. It is between a 1 and 5% loss in performance depending on the game.