Thanks for your input however my board is an Asus X99-E WS USB 3.1. All 7 of my PCIe slots are X16 Gen 3. My configuration is a Titan XP in slots 1 and 3 and the SM951 AHCI in slot 6. Even when I was running 3 980Ti’s in slots 1, 3 and 5 and a Intel 750 SSD in slot 7 I never had a reduction of speed. I think I’m going to just get rid of the SM951 AHCI and get another NVMe drive.
@JQS71
Usually it is recommended to plug in the SSD system (I assume i750 in your case) nearmost the last GPU.
Do you have the possibility to replace the SM951 AHCI device with a SM951 NVMe (same PCIe slot) ? (Same performance problem ?)
Do you have tested Samsung NVMe 960 EVO/PRO ?
Unfortunately I had the same results when I had the SM951 plugged into slot 5 which is the closest I can get to the last GPU. Also, I can not switch out with the other SM951 because it is located in the M.2 slot, and is my OS drive. I no longer have the Intel 750 SSD and these are the only 2 SSD’s in my system.
@JQS71
I have some doubt that your SM951 AHCI does not work properly. It is a very strong product.
May be, you should plug it into another PC, and do some benchs (CDM, ANVIL) with this device ?
I assume you know that even if you have 7 PCIe x16 "available" on the mboard and if some native M.2 slots are populated some "PCIe x16" becomes automatically disabled into BIOS.
On Sabertooth X99 I recommend to not use the M.2 slot for thermal reason and also for less performance (measured) in comparaison with an add-in card PCIe Gen 3 x4 solution.
Can you list in detail how are populated the the 7 PCIe x16 slots ? (free, if not free with what device). At the moment we have to guess your PCIe slots configuration.
Can you list the exact BIOS settings of "PCIEX16_1, _2,…,_7 Link Speed" into "NB PCIe configuration" sub-Menu of the "System Agent Configuration" Menu ?
I agree that it is not a hardware issue. I use to have this drive in my M.2 slot before I upgraded to the NVMe version and sold my Intel 750. I personally think it is driver related. Regarding your reservation towards not using the M.2 slot, my system is very cool. I have 4 Radiators in Push/pull and my case is enormous. I have never experienced throttling.
Answering your questions in order.
1. I have a Titan XP in slot 1, Slot 2 is empty, Titan XP in slot 3, slot 4 is empty, slot 5 is empty, slot 6 is empty, and the SM951 AHCI in slot 7.
2. In the BIOS I have tried setting the NB PCIe configuration to both Gen 3 and Auto. Neither resolved the issue so I changed back to Auto. I have gone through my BIOS settings thoroughly in the attempt to resolve the issue but nothing I tried or changed has resolved it. The issue is almost certainly related to my RAID arrays. Meaning instead of using the standard AHCI driver the drive is using the RAID driver. My reasoning is that the drive is running at SATA 3 speeds as opposed to PCIe X4 speeds.
@JQS71
Thnks for the details.
I assume Slot 2 and Slot 4 are empty due to mechanical reasons ? (may be Titan XP does need two slots (width) ?)
I assume you have disabled into BIOS all the empty slots excepted the slot associate to M.2 SM951 NVMe presence. What Slot number is it ?
By experience on my Sabertooth the NB “Auto” settings does not work, it is a bug I had reported to ASUS. The workaround is to set to “Gen 3” to force the right parameter value and this does works fine.
About your SATA RAID arrays I don’t understand your configuration.
To be more clear can you provide a “HWINFO64 / DriveControllerInfo” screenshot such as this one ?
@JQS71
Thanks.
I try to understand why you said the problem is coming from your RAID driver.
1) Why you don’t use Intel SATA RAID driver v13.2.4.1000 instead of v14.8.0.1042 ?
2) Can you develop your PCI Bus information such as:
On X99 mboard does exist 2 independant SATA Controllers, one is dedicated for AHCI and RAID mode configuration (v13.x), one other is exclusively for AHCI mode and does not support RAID mode (v5.x).
The SATA RAID driver I’m using is directly from the Asus’s support page. I have been doing a little more research and it looks like I am not the only person to have had this problem with X79 and X99 chipsets. The problem might be elated to the PCIe adapter that I am using. They both say they support PCIe X4 but it looks like they come in two variations. PCIe to SATA3 and PCIe to PCIe. I just ordered a new adapter that specifically states it will support the proper speeds. I’ll update when it arrives.
https://www.amazon.com/Asus-Accessory-32…l/dp/B017YUCAXS
@JQS71
1) you omitted to display me your PCIe Bus infos I was asking you such as these one relative to your SM951 AHCI device.
Which such infos you can observe if the device is properly connected with the proper driver and the proper BIOS settings:
2) To avoid any problem with PCIe V3.0 X4 add-in card I recommend you the perfect DUAL port support (SATA 6G and NVMe simultaneously) add-in card ECM20 M.2 Adapter SILVERSTONE.
or for a mono port solution SATA 6G or NVMe the LYCOM DT-120 (without radiator) or the KRYO M.2 PCIe v3.0 X4 for M.2 NGFF PCIe SSD (with radiator).
Hi,
Cansome 1 help me, becuz my ssd not reaching full speed, , and i dont know how to fix it, i have read most of topic in this forum, or maybe becuz of my mainboard,not support for max speeed, i installed in m.2 slot,
@DarkneZ :
Welcome to the Win-RAID Forum!
I have moved your post into this already existing thread with a rather similar title and hope, that this is ok for you.
Without detailed informations about your system and settings I cannot help you. What means “my SSD not reaching full speed”? Do you really think, that all Samsung SM951 SSDs (except yours) give their users the same benchmark results? That is an illusion.
By the way: Have you already done a look into the start post of >this< thread?
Regards
Dieter (alias Fernando)
@Fernando :
oh sry adn thanks,
i will check more threads first,
My Question:
- if my mainboard (m.2 slot) full supported for my sm951 for its max speed)
- dont know which driver i need, and if my setting correct or not, so can u pls check my system (u see em on my signature )
-maybe a fresh install for my system, and if possible i need all driver for my system, cuz i dont know which driver needed ( i used Driver Booster for my driver update or installed)
thx
Signature is wrong you should have the Samsung SM951, according to A SSD benchmark.
MZHPV256HDGL-00000
NVME driver:
http://www.samsung.com/semiconductor/min…load/tools.html
Motherboard is fine the m.2 slot support up to 10gb’s
Latest bios: X99-M-WS BIOS 3502.
Make sure m.2 is running in PCI/E mode and not sata mode 
(Should detect this on it’s own)
The m.2 slot is shared with the PCIE slot check out the NB PCIE configuration in the bios!
Manual:
http://dlcdnet.asus.com/pub/ASUS/mb/Sock…3443.1496223982
Bios updates:
https://www.asus.com/nl/Commercial-Serve…pDesk_Download/
Select DOS!
@Toetje583 :
Signatur fixed ,
i got the latest BIos also 3502,
when i tried to install the nvme driver: it say ssd not connected or so…
how can i check or setup to pcie or sata mode in BIos,cuz i cant find em,
and if i need NVMe driver ?cuz my sm951 is ahci?
i tried to reset/ clear the bios too, the first screen not detected the sm951 ,only my other sata hdd, thats normal or? cuz i can still install and run windows on my sm951,
Sorry my mistake you have the ACHI version not the NVME version.
Seems to be is it’s indeed running a bit slower then it should check out the PCIE configuration in bios, should be on auto!
I’m not sure the PCH storage configuration will list the M.2 slot on my asus board I have a separate menu for NVME drives, if you are able to boot from it you are fine!
EDIT by Fernando: Unneeded parts of the fully quoted post and unneeded blank lines removed (to save space)
In case of asus x99-m ws, they allocated x2 pcie 2.0 for onboard m.2, you would need a Asus Hyper m.2 X4 card and plug it into the last PCIE slot to get PCIE 3.0 
@Toetje583
i got the m.2 slot and i want to use it,
but if with this adapter, i can improve the perform of my sm951 or?
if yes i gonna buy 1, if rly needed,
and i should put it in last pci slot or the 2. one?
Here is a screenshot of a configuration test I have using SM951 AHCI 512GB as Boot System device on my X99 machine:
