How many NVME x4 drives can I connect to the Z390 at full speed?

[emil2424]

I have a Z390 AORUS ELITE so 2 NvME slots.

 

I'm currently using a Samsung 970 PRO x4 and would like to add a second NVME x4 drive.

Will the number of lines be divided into x2 + x2 after connecting second disks which will cause their speeds to be divided in half?

 

[Cyracus]

If you have no gpu you can run them full speed, or set the gpu to x8 (minimal if any performance impact) to run them at full speed.

Otherwise, chipset has 24 pcie lanes, with a gpu taking 16 lanes, you might think that means 8 lanes to split between your nvme drives, but alas other communications happen over those channels. So only one m.2 can run full speed with a gpu in x16 configuration, the other will be limited to x2.

[Electronics Wizardy]

20 minutes ago, Cyracus said:

If you have no gpu you can run them full speed, or set the gpu to x8 (minimal if any performance impact) to run them at full speed.

Otherwise, chipset has 24 pcie lanes, with a gpu taking 16 lanes, you might think that means 8 lanes to split between your nvme drives, but alas other communications happen over those channels. So only one m.2 can run full speed with a gpu in x16 configuration, the other will be limited to x2.

The m.2 slots and the gpu won't affect each other, the m.2 slots all run off the chipset lanes.

 

You can run both m.2s at pcie x4 speeds, but there limited by the chipset link, so there is a total of 32gbit to both drives. But this is very unlikely to be a issue.

[emil2424]

So if I work on one disk the speed will be maximum and if I use two at a time they will give a total of 32gbit.