M.2 NVMe RAID

[napper_tapper]

Hi guys, 

 

My motherboard is a Gigabyte AORUS (X470) Gaming 7 and I have a Samsung 970 EVO M.2 NVMe SSD (1Tb) that I currently fit into the top M.2 slot on the motherboard. The motherboard specifications lists this slot as:

 

M.2 connector (Socket 3, Key M, Type 2280, PCIe 3.0x4/x2 SSD Support).

 

There is a second M.2 port underneath this one that is listed in the specifications as:

 

M.2 connector (Socket 3, Key M, Type 2280, PCIe 2.0x4/x2 SSD Support). 

 

Does that mean if I were to populate the second M.2 port with another Samsung 970 EVO M.2 NVMe SSD (1Tb) that it would actually have a detrimental effect on read/ write speeds even if I was using them in RAID 0 by dropping the PCIe down to x2 only? Also is the main M.2 slot good enough to get the full potential out NVMe?

[NelizMastr]

6 minutes ago, rmurph17 said:

M.2 connector (Socket 3, Key M, Type 2280, PCIe 3.0x4/x2 SSD Support).

 

There is a second M.2 port underneath this one that is listed in the specifications as:

 

M.2 connector (Socket 3, Key M, Type 2280, PCIe 2.0x4/x2 SSD Support). 

 

Does that mean if I were to populate the second M.2 port with another Samsung 970 EVO M.2 NVMe SSD (1Tb) that it would actually have a detrimental effect on read/ write speeds even if I was using them in RAID 0 by dropping the PCIe down to x2 only? Also is the main M.2 slot good enough to get the full potential out NVMe?

This means slot 1 comes from the CPU and slot 2 comes from the PCH/chipset. Both can run at x4 speeds, but slot 1 does so at PCIe 3.0 which has twice the bandwidth. Your second slot will consequently run half the speed. 

 

For good measure:

 

1 PCIe 2.0 lane can do 500MB/s - an x4 SSD maxes out at 2GB/s - your 970 Evo does 3.4 read, 2.5 write. Bottleneck here is 1.4 on the read, .5 on the write.

 

1 PCIe 3.0 lane can do 985MB/s - an x4 SSD would therefore max out at just shy of 4GB/s, not bottlenecking at all.

[napper_tapper]

9 minutes ago, NelizMastr said:

This means slot 1 comes from the CPU and slot 2 comes from the PCH/chipset. Both can run at x4 speeds, but slot 1 does so at PCIe 3.0 which has twice the bandwidth. Your second slot will consequently run half the speed. 

 

For good measure:

 

1 PCIe 2.0 lane can do 500MB/s - an x4 SSD maxes out at 2GB/s - your 970 Evo does 3.4 read, 2.5 write. Bottleneck here is 1.4 on the read, .5 on the write.

 

1 PCIe 3.0 lane can do 985MB/s - an x4 SSD would therefore max out at just shy of 4GB/s, not bottlenecking at all.

So it is probably better just to stick with a single 970 EVO in the PCIe 3.0 lane so it is not bottlenecked? Thanks bro really appreciate the advice here on this one!

[NelizMastr]

13 minutes ago, rmurph17 said:

So it is probably better just to stick with a single 970 EVO in the PCIe 3.0 lane so it is not bottlenecked? Thanks bro really appreciate the advice here on this one!

Yep. I wouldn't bother unless both slots are 3.0 x4. 

[SSD Sean]

Yes, but in real world use 99% of the time there is little performance difference if you were to use the second slot instead. Sequential speeds only matter so much. Random speeds are hardly affected.