Maximizing M.2 NVMe Speed - Samsung SSD 970 EVO

Sep 24, 2018
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I recently installed a Samsung SSD 970 EVO 1TB SSD and I am trying to maximize read/write speed. Right now, the best I can get per Samsung Magician is:

Read speed 3149 MB/s
Write speed 2331 MB/s

I have the latest firmware and I am using the Samsung NVMe driver. The drive is connected via an adapter to a PCIe Gen 3x4 slot. TRIM is enabled.

Hardware specs are:

Gigabyte Technology Co., Ltd. Z97X-Gaming 7 x64-based PC
Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, 4001 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS American Megatrends Inc. F8, Fri Sep 18 2015
Installed Physical Memory (RAM) 32.0 GB
Windows 10 Pro x64

Link to motherboard specs page:
https://www.gigabyte.com/Motherboard/GA-Z97X-Gaming-7-rev-10#sp

Using a PCIe slot with the adapter gives better results than the M.2 slot on the motherboard (which is supposed to deliver up to 10 GB/s but doesn't seem to want to).

Can I do any better? What is the best install option for the driver (PCIe vs M.2 slot)? What BIOS settings should I double-check?

THANK YOU for any insights.

 
Solution
m.2 slot on most z97 motherboards used 2x PCIe 2.0 lanes. 1x PCIe is 5 Gbps. so, 2 paired together would be 10 Gbps. Z97 Allows upto 4 PCIe 2.0 lanes to be paired together (20Gb/s). but since only total of 8 PCIe 2.0 lanes are available on this chip-set motherboard manufacturers couldn't have just assigned half of the chip-set lanes to one connector and left almost nothing for rest of the devices.

Newer chip like z270, 370 and x299 have 24 lanes and they are PCIe 3.0. (8Gb/s per lane) you can also pair upto 4 lanes in these new chips. And since you have plenty of lanes it makes scene to assign maximum lanes to every m.2 connector/device. m.2 slot on newer motherboards can handle theoretical maximum of 32 Gb/s. And this what 960 and 970...
Sep 24, 2018
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Fair enough -- thank you. Any thoughts on why I'm only getting 827 read / 803 write when I put the drive into the M.2 slot on the motherboard (Magician reports that it is PCIe Gen 2 x 2)?
 

haseeb98ahm

Honorable
Jan 30, 2018
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m.2 slot on most z97 motherboards used 2x PCIe 2.0 lanes. 1x PCIe is 5 Gbps. so, 2 paired together would be 10 Gbps. Z97 Allows upto 4 PCIe 2.0 lanes to be paired together (20Gb/s). but since only total of 8 PCIe 2.0 lanes are available on this chip-set motherboard manufacturers couldn't have just assigned half of the chip-set lanes to one connector and left almost nothing for rest of the devices.

Newer chip like z270, 370 and x299 have 24 lanes and they are PCIe 3.0. (8Gb/s per lane) you can also pair upto 4 lanes in these new chips. And since you have plenty of lanes it makes scene to assign maximum lanes to every m.2 connector/device. m.2 slot on newer motherboards can handle theoretical maximum of 32 Gb/s. And this what 960 and 970 evo/pros are designed for.
 
Solution

R_1

Expert
Ambassador


I think you are confusing the BUS speeds with the device speeds.
its like the autobahn, just because there is no speed limit does not mean my moped will now do 235MPH. the device has a limit and that limit is well below the available bus.

GPU's for example do not need and cannot utilize all 16 lanes that the x16 slot provides. the devices are not there yet. they barely max out 8 lanes or 8x.

his device is working at the limits of the device, a wider bus assigned to it will do less than nothing.
the 970 can only R/W at 3.5 and 2.5Gb/s, so assigning another 10Gb to the speed limit is not helpful
 
You have done good and can't do gooder under the circumstances, of a slow PCIe 2 that supports the M.2 port versus the PCIe 3 support for the expansion slots. But the card values for read and write are spot on.

Go forth and enjoy !
 

haseeb98ahm

Honorable
Jan 30, 2018
102
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Op's original question was already answered. 3500MB/s read / 2500MB/s write are sequential max speeds for the SSD. Op then asked why speeds were slower on the motherboards m.2 slot. my reply is answering this question. (thought I should make this clear for anyone else who has the same issue)

Also also lowercase b in Mb/Gb means bits.
Gb= Gigabits
GB=Gigabytes

Mb=Megabits
MB=Megabytes