Using multiple M.2 SSDs on a Maximus XI motherboard

[Raja@ASUS]

And what about using two 970 EVOs in DIMM.2 slot, and the other two in a PCIE expansion card instead of onboard slots? Would this combination let me use the NVME SSDs full write and read speeds?

There are 16 CPU PCIe lanes. If you mount two X4 drives on the DIMM.2 module, it will occupy eight of them, leaving eight PCIe lanes for other cards. If you mount a further two X4 M.2 drives on a PCIe card, you will have no CPU PCIe lanes left for other cards (such as a graphics card).

For your info, the DMI Bus is limited to 32Gbps. That bandwidth is shared by all devices that are connected to the PCH. If the two onboard M.2 drives are not configured as a RAID array, access will be (or should be) independent, so the performance impact should not be large. If configured as RAID 0 array, reads will be bottlenecked by DMI bandwidth.

[PsiEmitter]

There are 16 CPU PCIe lanes. If you mount two X4 drives on the DIMM.2 module, it will occupy eight of them, leaving eight PCIe lanes for other cards. If you mount a further two X4 M.2 drives on a PCIe card, you will have no CPU PCIe lanes left for other cards (such as a graphics card).

For your info, the DMI Bus is limited to 32Gbps. That bandwidth is shared by all devices that are connected to the PCH. If the two onboard M.2 drives are not configured as a RAID array, access will be (or should be) independent, so the performance impact should not be large. If configured as RAID 0 array, reads will be bottlenecked by DMI bandwidth.

Thanks for your response! Would you please tell me: if eight PCIe lanes are used by the DIMM.2 module with 2xM.2 drives, does this have any effect on the speed of the graphics card installed in the x16 PCIe slot?

[Raja@ASUS]

Thanks for your response! Would you please tell me: if eight PCIe lanes are used by the DIMM.2 module with 2xM.2 drives, does this have any effect on the speed of the graphics card installed in the x16 PCIe slot?

If you use the DIMM.2 module, the primary PCIe slot will run at 8X. It doesn't impact performance by much.

[HiVizMan]

Thanks Raja for popping in. I had a good play last night and while I agree that there is a theoretical bottleneck I certainly did not experience anything in the real world stuff I played around with. However I was not using 4 Samsung 970's so I do not think that the four M2 that I used maxed out the bandwidth. RAID 0 was a piece of cake to set up by the way. Will do a guide when I get some free time.

So it is a resounding yes to the OP about can you do so. The VGA does run at 8x as has been said.

All in all very happy with the array (pun intended) of M2 options available on this board.

[PsiEmitter]

Thanks Raja for popping in. I had a good play last night and while I agree that there is a theoretical bottleneck I certainly did not experience anything in the real world stuff I played around with. However I was not using 4 Samsung 970's so I do not think that the four M2 that I used maxed out the bandwidth. RAID 0 was a piece of cake to set up by the way. Will do a guide when I get some free time.

So it is a resounding yes to the OP about can you do so. The VGA does run at 8x as has been said.

All in all very happy with the array (pun intended) of M2 options available on this board.

Hi! Thanks so much for your efforts and feedback! In the meantime I was considering not to use four M.2 drives, only three would be enough. So to summerize what I learned: is it fair to say, that the best possible solution for me would be to use two M.2 NVME drives in DIMM.2 socket, plus the third one in the onboard M.2 socket. And this way, I could use all three M.2 drives at their maximum speeds, while X8 PCIe speed on my GPU instead of X16 wouldn't result any noticable drop in my GPU's performance, even using an RTX 2080 Ti. Is that correct? Or can you perhaps recommend any other solution, that would be even better?

Thanks!

[Raja@ASUS]

That should be fine.

[HiVizMan]

Yip that is a very good configuration.

The difference in real world (games for example) performance with 16x v 8x is very small. Interestingly depending on the resolution of your monitor you may find that 8x delivers better performance. I discovered this when testing a Titan card at 16 x v 8x for the benchmark Unigine Heaven a few years back. But over all the difference so small that it is undetectable to the human eye.

[PsiEmitter]

Yip that is a very good configuration.

The difference in real world (games for example) performance with 16x v 8x is very small. Interestingly depending on the resolution of your monitor you may find that 8x delivers better performance. I discovered this when testing a Titan card at 16 x v 8x for the benchmark Unigine Heaven a few years back. But over all the difference so small that it is undetectable to the human eye.

Thank you! Can I ask, do you also use M.2 NVME SSDs in your own rig in the configuration we were talking about?

Oh, and one more thing. Do you recommend to use the two M.2 drives in DIMM.2 socket to be set up in Raid 0 in order to gain performance increase? I'm a bit confused, since some people suggest to do it, but others don't.

[HiVizMan]

Samsung PM981 NVMe PCIe M.2 1TB is what I use 24/7.

I have only had this motherboard that does have the DIMM.2 for 24 hours and spent most of yesterday doing testing for you with 4 older gen M2 drives.

So will find out how it goes later this weekend when I install my RAID 0 which is quicker. But dude, these M2 drives are so quick that honestly it does not matter where you install them. Just find the place that allows the easiest access is my view currently.

[PsiEmitter]

Samsung PM981 NVMe PCIe M.2 1TB is what I use 24/7.

I have only had this motherboard that does have the DIMM.2 for 24 hours and spent most of yesterday doing testing for you with 4 older gen M2 drives.

So will find out how it goes later this weekend when I install my RAID 0 which is quicker. But dude, these M2 drives are so quick that honestly it does not matter where you install them. Just find the place that allows the easiest access is my view currently.

Thanks really much for your efforts, I highly appreciate! Sorry for asking so many questions, but for me this is a good way to learn from you guys, who are much more experienced.

Is it fair to assume, that the DIMM.2 card OR a PCI-E M.2 NVME adapter card are completely equal in performance? I ask this, becouse for me the Maximus XI Extreme board's biggest advantage compared to Maximus XI Formula is the existence of the DIMM.2 slot. But since Extreme is far more expensive, IF a PCI-E M.2 NVME adapter card can run M.2 drives on the same performance level as a DIMM.2 card, then Formula could also be an equaly good alternative.

By the way, the reason I like the idea of these M.2 cards much better than using onboard slots, is becouse their cooling efficiency seems to be much better. After all, thermal throttling can also result performance drop.