Ramage VI Extreme and DIMM.2 Riser - best drive location

[mpoffo]

I have an Asus Rampage VI Extreme that I never put NVME in. I know, I know. I need to replace my main SSD windows drive and thought I would go with an Samsung 970 Evo Plus NVME.

I have a 7900x in the system so it should have 44 PCIE lanes.

Here is what I have installed in them on the board (From page 1-7 starting with the top slot going down)

PCIE_X16/x8_1 - RTX 3090 GPU

PCIEX8_2 - Empty

PCIEx4 _1 - VIVE Wireless Card

PCIE_x16/X8_3 - GTX 1080 GPU

PCIEX8_4 - Sound Blaster Z Audio Card

I simply want to add my 970 Evo Plus to my DIMM.2 riser and would like to know the best position to put it in so it won't disable any of the PCIE slots and give me good performance. I have read many older threads and there seems to be contradictory information and I simply want to get the best out of it without causing issues with anything else.

It appears if I put it in the M2_1 position on the DIMM.2 I could select CPU or PCH. If I select PCH then it disables my PCIEx4 above (no go for me)? If I select CPU then it would disable the U.2 (which I don't use)? Which is better PCH or CPU?

If I select the M2_2 position it would be PCH or CPU? I read that is shares bandwidth with the PCIX8_4 slot (bottom slot), so PCH?

Right now it appears that the M2_2 slot might be the better option or M2_1 via CPU.

I should have the PCIE lanes available for this but I could used some assistance to make sure I am selecting the best option and looking at this correctly.

Thanks

[xeromist]

To answer one of your questions: Which is better PCH or CPU? A direct pipe to the CPU is going to be better in situations where you don't give up anything else. A simple build with few devices is going to have extra unused lanes so you might as well allocate them directly when possible. PCH has a fixed number of lanes it shares out to connected devices. This is fine most of the time because not everything is using a lot of bandwidth at the same time. At times there may be high utilization from multiple devices and they will slow each other down. Typically this isn't even noticeable.

On the other hand, if you have to disable other slots in order to give your NVME a dedicated pipe, is it worth it for you? Typical users will have storage usage between idle and low the vast majority of the time. In rare situations there might be a flurry of activity performing mass file operations but those are usually few and far between. And as mentioned, most people won't even notice if there is resource contention.

[mpoffo]

xeromist wrote:
To answer one of your questions: Which is better PCH or CPU? A direct pipe to the CPU is going to be better in situations where you don't give up anything else. A simple build with few devices is going to have extra unused lanes so you might as well allocate them directly when possible. PCH has a fixed number of lanes it shares out to connected devices. This is fine most of the time because not everything is using a lot of bandwidth at the same time. At times there may be high utilization from multiple devices and they will slow each other down. Typically this isn't even noticeable.

On the other hand, if you have to disable other slots in order to give your NVME a dedicated pipe, is it worth it for you? Typical users will have storage usage between idle and low the vast majority of the time. In rare situations there might be a flurry of activity performing mass file operations but those are usually few and far between. And as mentioned, most people won't even notice if there is resource contention.

Thanks very much for your reply. Do you happen to know if the 2nd DIMM.2 slot (facing the power connectors) on the riser for the Rampage VI Extreme is CPU or PCH?

[sultan_of_swing]

Both DIMM.2 slots are direct to CPU.

[mpoffo]

sultan.of.swing wrote:
Both DIMM.2 slots are direct to CPU.

OK I know the 1st one you can select PCH or CPU in Bios. So the second one is tied to the CPU.

Thanks

[sultan_of_swing]

I think it depends on how you have the bios setup and the cpu you have, there is a drop down selection so you can choose the PCI-E layout.
To enable the 2nd dimm.2 slot you have to select anything other than 16x/16x/8x for 44 lane cpu's