[SOLVED] Using two NVME SSDs

[ldaneels]

I am not 100% sure how this works, so the question might be pointless, but I can't seem to find a straight answer anywhere, so here it goes
I would like to use 2 NVME SSDs and would like to make sure they both run at their max speed (so, using PCIE 3.0 x16). As I understand, the full PCIE speed is shared among ports (x16 for the PCIE for the GPU, x16 for 1 NVME slot & x4 for the second NVME slot,...), so if I have a GPU + one NVME, the second NVME would not run at full speed. Am I understanding this right? Are there motherboards that would support multiple NVME (at least 2) running at full speed along with a modern GPU (RTX or Vega)? Would it require multiple CPUs since they are controlling the PCIE lanes?
Any help would be greatly appreciated.

 

[kanewolf]

Currently NVMe storage is PCIe 3.0 x4. You need a CPU and/or motherboard with 8 PCIe lanes dedicated to M.2 slots. A Threadripper motherboard would have plenty of PCIe lanes to provide that. Some Z390 motherboards have two M.2 PCIe x4 slots. It does not require dual socket, just careful reading of the specs.

 

[ldaneels]

Ok, I think my issue comes from the inconsistant use of the x4/x16 designations on specsheets and merchant websites, or maybe simply my misunderstanding. So, reading the i7 9700K specs, it says that the CPU has a max of 1x16/2x8/1x8+2x4 configuration.
So, basically the GPU would need a x16 PCIE and each NVME a x4 PCIE, right? In that case, how would that work with any of the mainstream CPUs? Are the GPU lane & other PCIE lanes separate? What controls each lane?
The problem with the motherboards is that the info is generally rather fuzzy & can be interpreted different ways (or at least I can't seem to make heads or tails). Especially since some configurations can be deactivated depending on what populates these PCIE slots. Talk about a nightmare trying to understand this...
To make things a bit more practical, I was targeting an i7 9700K (or anything that might come next from Intel if it's decent) and an ASUS motherboard (mainly due to brand loyalty). Any combination that would work with my goal (2 NVME SSDs running at their designated speed + one modern GPU).
Thanks in advance.

 

[kanewolf]

Ok, I think my issue comes from the inconsistant use of the x4/x16 designations on specsheets and merchant websites, or maybe simply my misunderstanding. So, reading the i7 9700K specs, it says that the CPU has a max of 1x16/2x8/1x8+2x4 configuration.
So, basically the GPU would need a x16 PCIE and each NVME a x4 PCIE, right? In that case, how would that work with any of the mainstream CPUs? Are the GPU lane & other PCIE lanes separate? What controls each lane?
The problem with the motherboards is that the info is generally rather fuzzy & can be interpreted different ways (or at least I can't seem to make heads or tails). Especially since some configurations can be deactivated depending on what populates these PCIE slots. Talk about a nightmare trying to understand this...
To make things a bit more practical, I was targeting an i7 9700K (or anything that might come next from Intel if it's decent) and an ASUS motherboard (mainly due to brand loyalty). Any combination that would work with my goal (2 NVME SSDs running at their designated speed + one modern GPU).
Thanks in advance.

The CPU isn't the only chip that has PCIe lanes. The motherboard chipset has PCIe lanes. The USB, ethernet, SATA and NVMe all get their I/O from the motherboard chipset. So the CPU PCIe lanes are mapped to the slots on the motherboard and not the other peripherals. Look for a block diagram of the Z390 chipset and you will see what I am talking about.

 

[ldaneels]

Hi, thanks for the info. That being said, I am not super proficient in computer tech... While I can piece things together most of the time, I do need a bit more direction.
So let me try to rephrase what I understand (hopefully I'm not too far off the mark...):
- in my case, the 9700K has x16 PCIE lanes, which would be mapped to the PCIE slots (where you plug the GPU/PCI cards/Optane SSD drives) but nothing else. So, in essence, if I had multiple GPUs, the CPU would take care of one and the motherboard of another (and it would take from a pool of up to 24 PCIE lanes as per the block diagram), right?
- If I take the Asus ROG Strix Z390-E (https://www.asus.com/us/Motherboards/ROG-STRIX-Z390-E-GAMING/), there are two PCIE 3.0 x4 M.2 slots available for NVME which would allow me to use both NVME drives at optimal speed. That being said, these two x4 slots would come from the "up to 24 PCIE lanes" shown in the block diagram for the Z390 chip, so that would leave x16 lanes free for anything else I would want (but not NVME since there are only two M.2 slots)
Let me know if I'm on the right track or if I misunderstood something. If I did, please go into details so I can grasp what I'm missing.

 

[kanewolf]

If you have two GPUs this is where the "1x16/2x8/1x8+2x4" comes in. The PCIe lanes from the CPU get distributed to the two GPUs as x8 and x8.

The Asus Z390-E motherboard -- The PCIe lanes for the NVMe come from the chipset. But that doesn't mean the other x16 are available. They are statically mapped to USB ports and ethernet and SATA ports. And per the note one of the SATA ports is disabled.

If you installed a third card in the third x16PCIe slot, then the three cards would be x8, x4, x4. The PCIe x1 slots might come from the CPU or chipset. I don't know.

 

[ldaneels]

Cool, thanks for the answer, I think I finally got it