M.2 Not full speed

anything I don't mind · 11 Sep 2015 at 11:22

This guy at work who i helped purchased a new motherboard for has a m.2 slot on his new motherboard and a new m.2 ssd.

I was hoping he would get 1500mbyte a second from it but using benchmark software it seems to max out at 700mbyte a second.

Samsung SM951 256gb
Gigabyte z97x-ud4h-bk

He said there is nothing in the bios for m.2 as he was looking for something that might change the m.2 slot to a faster setting.

Is there anything we are missing as to why this is not full speed?

Pyr0m@nI@]{ · 11 Sep 2015 at 11:26

Sounds about right to me tbh.
Looking at the Z97X-UD5H-BK (couldn't see the ud4) those boards only have 10Gb/s M.2 slots

http://www.gigabyte.com/products/product-page.aspx?pid=5378#ov

M.2 for SSDs drives with up to 10 Gb/s data transfer

anything I don't mind · 11 Sep 2015 at 11:51

Pyr0m@nI@]{;28550924 said:
Sounds about right to me tbh.
Looking at the Z97X-UD5H-BK (couldn't see the ud4) those boards only have 10Gb/s M.2 slots

http://www.gigabyte.com/products/product-page.aspx?pid=5378#ov

So what do you need to get 1500mbyte speeds then?

Biomorphs · 11 Sep 2015 at 11:51

OCUK lists the Drive as 'Samsung SM951 256GB M.2 PCI-e Gen3 8Gbps '

And posts speeds of:

Read Speed: 2150MB/s
Write Speed: 1200MB/s

So if that's 8Gbps with those speeds, and the slot supports 10Gbps then is something not wrong? what motherboard do you need to get these speeds??

lsg1r · 11 Sep 2015 at 11:58

sounds like it's running in 'sata' rather than 'pcie'....

Are you 100% sure the board you have supports higher speed connections over the m2 slot and as a side thought, is there enough bandwidth for it to run at full speed, sli for example could slow it down due to not enough pcie bandwidth to go around.

anything I don't mind · 11 Sep 2015 at 12:13

The motherboard comes with its own m.2 slot. This is meant to by pass any pcie bandwidth limitations.

.:SAmSuNG:. · 11 Sep 2015 at 12:34

If its the same as my Z97 m.2 slot which 95% it is, you are limited to that speed because it runs though the Sata part of the board.

The way to get full speed is to buy a PCI-E card and stick it in something like this:

https://www.overclockers.co.uk/showproduct.php?prodid=HD-011-PL&groupid=701&catid=2104&subcat=2198

ocuk did have them just the board for maybe a fiver or a tenner but can find them. I bought mine elsewhere.

But this will limit your other x16 slot to x8 which you may or may not care about. Ive used both ways and really not much difference in normal feel of the system. I use it in the m.2 slot now so only 730mbps but means I can run two gpu's.

X99 or skylake m.2 is only way to get full speed mounted directly to the mobo.

lsg1r · 11 Sep 2015 at 12:35

anything I don't mind said:
The motherboard comes with its own m.2 slot. This is meant to by pass any pcie bandwidth limitations.

only if it has an extra chipset involved, there's only so many lanes that the cpu can supply on it's own so if you have sli then you could be restricting the m2 slot's pcie. Now I'm not saying this is the case in your situation, we don't know much about the pc but it would fit the issue in my opinion.

The 4th/5th gen cpu's that the motherboard supports has 16 lanes for pcie meaning in sli you would get 2x8 (total 16) being used by the gpu's.

The m2 would then be controlled via the sata controller (iirc) meaning less bandwidth and slower speeds for the drive. Remember it says upto 10GB/s.

If the rig is running sli, try taking one gpu out and see if the performance improves

anything I don't mind · 11 Sep 2015 at 12:44

It is not running SLI it has one 7950 in it.

.:SAmSuNG:. · 11 Sep 2015 at 12:54

Read my post.

FredFlint · 11 Sep 2015 at 13:03

Biomorphs said:
OCUK lists the Drive as 'Samsung SM951 256GB M.2 PCI-e Gen3 8Gbps '

And posts speeds of:

Read Speed: 2150MB/s
Write Speed: 1200MB/s

So if that's 8Gbps with those speeds, and the slot supports 10Gbps then is something not wrong? what motherboard do you need to get these speeds??

It should be 8Gbps * 4 = 32GBps as each PCIe Gen 3 lane is 8Gbps and it can use 4 lanes. To get full speed on a Z97 you need to use a PCIe 4x Gen 3 to m.2 adapter card.

anything I don't mind · 11 Sep 2015 at 13:50

FredFlint said:
It should be 8Gbps * 4 = 32GBps as each PCIe Gen 3 lane is 8Gbps and it can use 4 lanes. To get full speed on a Z97 you need to use a PCIe 4x Gen 3 to m.2 adapter card.

Strange, so even though the MB comes with an M.2 slot, he would still benefit from a pcie 4x card with an m.2 slot?

I have this motherboard, Gigabyte GA-Z87X-UD4H

Could i purchase the same card (eg Lycom DT-120, PCIe 3.0 x4 Host Adapter) and get full speed m.2 as well?

Ok well thanks for explanations. I understand.

ZXSpectrum · 11 Sep 2015 at 15:13

anything I don't mind said:
Strange, so even though the MB comes with an M.2 slot, he would still benefit from a pcie 4x card with an m.2 slot?

I have this motherboard, Gigabyte GA-Z87X-UD4H

Could i purchase the same card (eg Lycom DT-120, PCIe 3.0 x4 Host Adapter) and get full speed m.2 as well?

Ok well thanks for explanations. I understand.

Yes unfortunately unless the board has a dedicated 32Gbps m.2 the SM951 will not run at full speed. It will run up to the maximum that the slot can handle which works out to about 700-800Mbps. The Z97 as standard doesn't come with the 32Gbps.

.:SAmSuNG:. · 11 Sep 2015 at 17:37

anything I don't mind said:
Strange, so even though the MB comes with an M.2 slot, he would still benefit from a pcie 4x card with an m.2 slot?

I have this motherboard, Gigabyte GA-Z87X-UD4H

Could i purchase the same card (eg Lycom DT-120, PCIe 3.0 x4 Host Adapter) and get full speed m.2 as well?

Ok well thanks for explanations. I understand.

Im not sure boards before Z97 will boot from the host adaptor. Some Z97 boards are abit funny sometimes.