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M.2 SSD's on the Sabertooth X99 - SLOW

Level 7
Hey guys,

Morning 😛

Just built my new rig (details bottom of post).

I have two Samsung 951 NVMe drives - one in the dedicated M.2 socket (256GB SSD) and one on an expansion card connected to the PCIex 4_1 socket (128GB SSD).

The 128GB drive (OS) is running OK - way short of review benches - but seems fast enough.
The 256GB drive (Programs) on the M.2 slot is incredibly slow - it's currently benching slower than my Samsung Evo SSD connected through regular SATA.
And it really shows.

I did a user benchmark and compared the drives against identical systems:

128GB benching at 140% - average 170% - highest 216%
256GB benching at 64% - average 198% - highest 264%

Crystalmark scores for the 256GB drive:

Sequential Read (Q= 32,T= 1) : 417.645 MB/s
Sequential Write (Q= 32,T= 1) : 326.922 MB/s
Random Read 4KiB (Q= 32,T= 1) : 407.576 MB/s [ 99505.9 IOPS]
Random Write 4KiB (Q= 32,T= 1) : 323.379 MB/s [ 78950.0 IOPS]
Sequential Read (T= 1) : 387.798 MB/s
Sequential Write (T= 1) : 308.925 MB/s
Random Read 4KiB (Q= 1,T= 1) : 45.959 MB/s [ 11220.5 IOPS]
Random Write 4KiB (Q= 1,T= 1) : 94.739 MB/s [ 23129.6 IOPS]

Test : 1024 MiB [D: 16.6% (39.7/238.3 GiB)] (x5) [Interval=5 sec]
Date : 2016/02/08 11:26:29
OS : Windows 10 Professional [10.0 Build 10586] (x64)

I'm at a loss to understand what's going on - BIOS (2101) is reporting both drives as NVMe.

I set SATAExpress_1 SRIS Support in the BIOS to disabled which improved the speed (slightly) of the 128GB but no change to the 256GB.
Installed the Intel drivers as i believe Samsung doesn't make NVMe drivers.

AFAIK the 5820 CPU has 28 lanes - i'm running one GPU on the 16_1 - which should leave 12 lanes free - so i expected the two M.2 drives to pick up 4 lanes each.
It seems like the expansion card with the 128GB is getting 4 lanes but the 256GB in the actual M.2 socket isn't!

Although no idea why the 256GB should be running much slower than my EVO connected through regular SATA.

The only ideas i have are:

Should I move the expansion card with the 128GB to another PCIex scocket i.e. 16_2 or 16_3?
I have a samsung Evo connected to SATA port 7 on Sata controller 2 - could that be interfering with the M.2 socket bandwidth - maybe if i moved it to another port/controller?

Any suggestions or ideas totally appreciated.... Cheers


Intel i7 5820K (base clock)
Asus Sabertooth X99
16GB Corsair Vengeance 2666
EKWB Predator 360 Liquid (CPU and GPU)
Samsung SM951 128GB M.2 PCI-e NVMe SSD (OS)
Samsung SM951 256MB M.2 PCI-e NVMe SSD (Programs)
Samsung Evo 250GB SSD (Documents)
2 x 3GB Western Digital Red HDD (RAID 1) (MEDIA)
Coolermaster Haf-X