You would need to look in the BIOs to see if such a setting for higher PCIe link speed exists.

Also im wondering if i messed something up installing the intel rst drivers after the clean windows instal. Mabey it already had what it needed and i installed old drivers over the new ones, im not sure because i did'nt check the speeds or see if intel rst drivers were already there. I was just going into "install drivers after new windows install mode" and got a little ahead of myself. I only say this because there was a bios update for my computer that was after the driver update signature on the intel rst drivers i installed. And since the raid 0 was setup within the new bios, and windows install did not prompt me for any kind of raid drivers, maybe it was the correct speed before my dummy self installed the Intel rst drivers without checking first. ??? mabey?
 
So since im really trying to do this windows install exactly how i want to do it, to reduce clutter, misplaced files, and installing-uninstalling things i need and leaving files behind, etc., etc.
Im thinking of just redoing the whole reinstall, and trying again -and key point here- check before installing old, outdated, wrong, or un-needed drivers i don't need or that are already installed to mess things up.... lol.
 
I hav'nt started reinstalling any of the big file size stuff yet, was transferring a file of drivers back to the main harddrive after raid setup/new install and noticed it was going really slow. Thats when i thought, hey i should install "intel rst drivers" :l

That seems to be the case here as well.

There is two m.2 slots. Not sure if both are the same speed or if one is a sata 3 with a m.2 connector.   Hav'nt been able to find strait answer from research.
Here's what i can tell you. I was getting around 1500 on crystal disk mark on stock setup with one pm951.  Setup in raid 0, reinstalled windows etc. Then ran benchmark with it in raid 0. Now granted this was a fresh install of windows not fully updated yet. (don't know if that makes a difference) and i was getting around 2600 on crystal disk mark. (the numbers are from the top left read speeds on the stock crystal disk mark test)
Everything is running great. And to answer the why question. Although a lame answer, simply i have never setup anything in raid before. Pretty much that simple. I understand the consequences and just wanted to test it out. I use my computer for gaming, so having the two drives as one combined storage saves me alot of headache. Also i have a third ssd drive (500gb ssd) that i save anything that is'nt a game file to. I have windows folders ( downloads, documents, pictures, videos, etc. ) all setup to default save to the ssd backup drive instead of the main raid 0 drive.
All game files i have are easily obtained by redownloading from my steam, origin, blizzard, game providers. So no threat of any data loss.
So aside from the fact of not knowing the actually capability of the second drive slot in terms of x2 or x4, everything seems to be running as should be. No problems, hang ups, glitches or anything. So ill keep it going and see what happens. 
So last question what would be the normal read speeds of two pm951's in raid 0 in a rig that confirms both ports are x4 speeds?

I looked in bios, both drives are recognized as PCIe NVMe drives in raid 0 when i look at the details of each drive individually. I only have two m.2 slots they are side by side, and one sata 3 ssd slot.
Heres a couple screenshots of the differences of the speeds of the drives. First one is a benchmark of each drive individually setup normal then the second is the benchmark after it was setup in raid 0. I have no clue if this is what it is suppose to look like.

Both only have the one notch. Not sure why intel rst  says it that way, could just be the intel rapid storage drivers reading it wrong.
Here's the benchmark again after i installed windows and all my games back. (I tried to post two pictures last time but it's only showing the benchmark of the two individual drives setup normally.) Here's the raid 0 speeds

There are not enough PCIe lanes to hook both up at x4, one slot has x4, one slot has x2. It's a hardware limitation, nothing will change it.
 
RAIDing NVMe SSDs is kind of pointless on a desktop system IMHO, doubt you could even tell the difference.

No this is an alienware 17 r3 (early 2016 skylake) laptop.   It has three drive slots.  Two are m.2 connections that are side by side. And there is an additional sata 3 slot as well. I have the two m.2 slots filled with samsung pm951 in raid 0 and the sata 3 slot has a kingston hyperx savage 480gb ssd for saving all data that i don't want to loose.
Even thought the two m.2 slots are different speeds, it's showing around 2900 read and about 1100 write in raid 0.

will check when i get home. With it showing 2900 read and 1100 write im inclinded to believe it is setup correct with x4 on both. But will check it out with crystal disk info and see what it says.
 

Strange.

LittleGuy
There are only 16 PCIe Lanes with HM170, which would mean 8 for the GPU, 4 for the EGPU and 2 each for the PCIe SSD's. 
 
So you said there is another drive in there than I would say that drive is taking the other 2x pcie lanes for a total of 16 lanes if that motherboard only has 16.
 
http://forum.notebookrevi...sd-specs.782523/page-2
Chipset only has 16 lanes
https://ark.intel.com/pro...le-Intel-HM170-Chipset

GPU gets its lanes from the cpu which has 16 also. South bridge chip (hm170 in this case ) will have 16 for everything else.

LittleGuy

quadlatte

LittleGuy
There are only 16 PCIe Lanes with HM170, which would mean 8 for the GPU, 4 for the EGPU and 2 each for the PCIe SSD's. 

So you said there is another drive in there than I would say that drive is taking the other 2x pcie lanes for a total of 16 lanes if that motherboard only has 16.

http://forum.notebookrevi...sd-specs.782523/page-2
Chipset only has 16 lanes
https://ark.intel.com/pro...le-Intel-HM170-Chipset

GPU gets its lanes from the cpu which has 16 also. South bridge chip (hm170 in this case ) will have 16 for everything else.

Ok, this is from Dell forums. https://community.dell.com/thread/19472
alienware 17 R3 which both have the same motherboards, have two m.2 slots.  One of the two slots supports both Pcie X4 and SATA III as the m.2 interface can support either sata or Pcie.
The second m.2 slot supports ONLY sata III and/or Pcie x2.  
To repeat, one of the slots supports 4 lanes of Pcie, the other supports only 2 lanes of Pcie.  Both slots support Sata III.
This means you can use the 850 EVO sata drive in either slot, or the 950 pro in either slot, however, in one slot the 950 pro will ONLY have 2 Pcie lanes available to it so it will not work at its top speed.  In the other slot it will have 4 Pcie lanes available to it and will work at its top performance.
 

figured thats what they did. still x2 should be pretty fast with around 1800MBs theoretical speed. so the speed the OP is getting is about right since it will max out at the x2 slot so the x4 slot can only run at that speed also.

That 950 is fast!!    The main reason i went the way i did and just bought another 512gb pm951 is i only paid $100 bucks for it. Someone i know bought a system and first thing they did was replace the m.2 drives so i grabbed one up. So everything is working good so far. I guess the looming day raid 0 decides to act up is the day i'll stop using raid 0 configuration and just go buy some big 950's.
Mabey by then they will be cheaper.