ASUS Z97-P: Samsung SM951 appears to use SATA instead of PCIe

mffinn

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Jun 28, 2015
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4,510
I just put together a 4790K, 16GB RAM and a 128GB Samsung SM951 SSD on an ASUS Z97-P motherboard. I didn't change any UEFI BIOS defaults and then installed Windows 8.1 from a USB stick. All went fine.

I then ran Piriform Speccy and it said that the SSD was connected via SATA (I'm expecting to see PCIe). I then ran HDTune Pro to benchmark the SSD and it returns speeds around 570 MB/s (I would expect to see something a bit closer to the advertised 2,000 MB/s for this SSD).

After some googling I went into the BIOS but I don't see the same settings that other people report on other Z97 motherboards. I do see options for the 4 SATA devices but under M.2 it just says 'empty'.

The specs for the mobo clearly state that PCIe is supported on M.2 and the SM951 clearly states it supports it as well.
What do I have to do to get this SSD working optimally on this mobo?

thanks in advance
 
Solution
You certainly can't expect that to work correctly by installing with BIOS default settings.

Manual
http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z97-P/E9385_Z97-P.pdf

2.8.9 CSM set to [Disable]
Boot Device Control set to [UEFI Only]
Boot from Storage Devices set to [UEFI Driver First]
Boot from PCI-E/PCI Expansion Devices set to [UEFI Driver First]

2.8.10
Secure Boot
OS Type [Windows UEFI Mode]
Install Default Security Keys

Intstall Windows 8.1 by choosing UEFI when given that option.
You certainly can't expect that to work correctly by installing with BIOS default settings.

Manual
http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z97-P/E9385_Z97-P.pdf

2.8.9 CSM set to [Disable]
Boot Device Control set to [UEFI Only]
Boot from Storage Devices set to [UEFI Driver First]
Boot from PCI-E/PCI Expansion Devices set to [UEFI Driver First]

2.8.10
Secure Boot
OS Type [Windows UEFI Mode]
Install Default Security Keys

Intstall Windows 8.1 by choosing UEFI when given that option.
 
Solution

mffinn

Reputable
Jun 28, 2015
2
0
4,510
Thanks for the response.

Seems that default BIOS settings are just fine and this setup is actually OK. This motherboard does not get the maximum read speed from this SSD because it only has two PCIx2 lanes for the M.2 slot: http://techreport.com/review/28036/asus-z97-p-motherboard-reviewed

I did another UEFI Windows reinstall after changing settings as you suggested and ran the benchmarks again. I still got 560MB/s in HDTune but 686MB/s in Crystal and 756MB/s in ATTO (which uses compressible data). These are the absolute top end of the range for SATA3 and pretty good for PCI-E 2.0 x2 so either way I assume I'm getting as much as I can out of this SSD with this motherboard:
https://www.ramcity.com.au/blog/m.2-ngff-ssd-compatibility-list/189
http://www.thessdreview.com/our-reviews/samsung-sm951-m-2-pcie-ssd-review-512gb/2/