Multiple M.2 motherboard that doesn't share bandwidth?

[jackharris27]

I'm looking to replace an Asus X99a motherboard with the i7 5280k cpu and im running into a few confusing snags. I went out and bought an asus Z490E ROG board amd a i7 10700k recently and returned it because I am trying to run 2 m.2 nvme drives but only 1 will get full speeds while the other is over HALF the speed. Turns out that the board/cpu shares the bandwidth or something (sorry I'm not extremely versed in the jargon). So now I'm eyeballing an AMD build with a 5800x and a pcie 4.0 board. Probably a gigabyte? 

 

My main question is this. Is there a PCIE 4.0 motherboard/cpu that will support dual NvME m.2 drives at full speed each? Ive currently got a 500gb Samsung 970 evo m.2 and added a 1tb version of the same (not trying to run a raid configuration because i don't know enough about raid setup for gaming.) But returned that 1tb unit with the i7 and asus board. Ive also got the coins set aside for a 3080 or a 6800xt once they become available. Please keep the responses in layman's terms as I try not to mess with over clocking and voltages because I don't want to fry anything prematurely. I'm not into that side of pc gaming enough. Thank you so much for the info in advance!

[SupaKomputa]

I don't know why you get half speed for the second slot. Both have pci-e 3.0.

The ports are not sharing the lanes. The 1st one gets its lanes from the CPU and the other got its lanes from the chipset.

So it suppose to run at full speed in all slots.

If you're using 970 evo you will not be using pcie 4.0 speed, as the drive is a pcie 3.0.

Full atx AMD boards usually have 2-3 m.2 slots being 1 connected directly to the cpu.

I suggest getting a X570 board if you want full pcie 4.0 support for all the slots.

[jackharris27]

Its abstract in the manual but the ROG z490 board i had, shares the lanes on the m.2 so when I would test them one m.2 (samsung evo 970 500gb) I'd get full speed but the Samsung 970 evo plus 1tb would get half speed. I swapped them and it was the same thing. I could get full speeds on slot 0 for the m.2, and again half speed on slot 1. What I want is a board where I can use 2 m.2 drives simultaneously at full speeds

[jackharris27]

Bump?

Someone has to know