M.2 SSD with PCI-E adapter? Worth it?

[Arthur_S]

Hello. I wanted to buy a new SSD and saw that there are now some type of M.2 SSD with huge speeds (2k read 1k write).
My motherboard (Gigabyte F2A88XM-D3H) doesn't have an M.2 slot. Would it be a good idea to buy a M.2 PCI adapter? (link- I only found this in my locak store DeLOCK 89370 interner M.2 Adapter für PCIe x4)

II don't know if it's a good idea to put this PCI card because I have an MSI R9 380 GPU, would it overheat somehow m.2 ssd?

 

[Shaun o]

Well a M2 slot on a motherboard actually runs on the Pci-e express lanes anyway of the motherboard.
Using a M2 card on a pci-e expansion card to a free Pci-e slot gives you exactly the same data bandwidth as the M2 slot it`s self on a motherboard equipped with one.

There is no difference you should get the same raw transfer speeds as a dedicated M2 slot on a mobo.

 

[ThomasLeong]

According to your motherboard specs, that second slot is PCIe 2.0x4, not PCIe 3.0x4 . So an M.2 that is rated for PCIe3.0x4 will only run at lower speeds, probably around 10Gb/s instead of 32Gb/s. You will not get the "2k read 1k write" that you have read about (thinking of the Samsung range are you?). The Plextor range of M.2 is rated at PCIe2.0x4. Still faster than SATA's 6Gb/s.

 

[Arthur_S]

According to your motherboard specs, that second slot is PCIe 2.0x4, not PCIe 3.0x4 . So an M.2 that is rated for PCIe3.0x4 will only run at lower speeds, probably around 10Gb/s instead of 32Gb/s. You will not get the "2k read 1k write" that you have read about (thinking of the Samsung range are you?). The Plextor range of M.2 is rated at PCIe2.0x4. Still faster than SATA's 6Gb/s.

thank you for poiting me up to this. I was sure that I have all PCI-E 3 slots. That's ad that they are pci2, I guess I should just get a sata3 ssd instead.

 

[The Original Ralph]

running in a PCIe x4 expansion slot (by use of the adapter) should give you full speeds. I've got a samsung xp941 (first gen PCIe SSD) running in an addionics expansion card on an ASUS Z97M-Plus motherboard.

when i tried it in the M.2 slot. which is x2 or 2 lanes, my read / write speeds were 770 MB/s read, 580 MB/s write

When i installed it in the PCI expansion card, speeds jumped to full specs, 1180 MB/s read, 870 MB/s write

Additionally most Z97 motherboards, use of the M.2 socket dis-ables 2 sata ports, so using the expansion slot had an addtional benefit, enabling use of the two lost sata ports

 

[ThomasLeong]

Question to The Original Ralph:
Did you install the M.2 PCIe Adapter Card in the first or the second x16 slot of the Asus Z97M-Plus?

From the results you posted, I would guess the Card is installed in the first slot (usually used for a graphics card), i.e. you are not using a 3rd party graphics card but using the Z97 on-board graphics instead. This first slot is PCIe 3.0.

The second slot is PCIe 2.0 at x4 lanes, similar to Arthur_S's Gigabyte F2A88XM-D3H. And Arthur_S has a MSI R9 380 GPU occupying the first slot, so he would have to install any M.2 PCIe Adapter Card in the second slot unless he is willing to forego the MSI R9 380 GPU.

Re the Asus Z97M-Plus. Nice mobo but, as you discovered, the M.2 slot is PCIe 2.0x2 similar their expensive X99M-WS, which is a disappointment since an Intel LGA2011 cpu has more PCIe 3.0 lanes than a LGA1150 cpu, and Asus chose not to allocate 4 of those lanes to the M.2 slot.

 

[The Original Ralph]

Question to The Original Ralph:
Did you install the M.2 PCIe Adapter Card in the first or the second x16 slot of the Asus Z97M-Plus? - actually in the last slot which is PCI x4 (i assume that it's PCI 1.0 - nothing in the manual gives any indication)

From the results you posted, I would guess the Card is installed in the first slot (usually used for a graphics card), i.e. you are not using a 3rd party graphics card but using the Z97 on-board graphics instead. This first slot is PCIe 3.0. NO - see above response and my system specs in my signature

The second slot is PCIe 2.0 at x4 lanes, similar to Arthur_S's Gigabyte F2A88XM-D3H. And Arthur_S has a MSI R9 380 GPU occupying the first slot, so he would have to install any M.2 PCIe Adapter Card in the second slot unless he is willing to forego the MSI R9 380 GPU. I couldn't access the 2nd slot as it is covered by my GTX 750 Ti video card

Re the Asus Z97M-Plus. Nice mobo but, as you discovered, the M.2 slot is PCIe 2.0x2 similar their expensive X99M-WS, which is a disappointment since an Intel LGA2011 cpu has more PCIe 3.0 lanes than a LGA1150 cpu, and Asus chose not to allocate 4 of those lanes to the M.2 slot.

AGREED

I suspect when i install a 950 PRO NVMe SSD, i'm going to have to decide if i want to keep that video card or remove it to give me access to that PCIe 3.0 slot

 

[ThomasLeong]

Ah, we have a bit of a mis-read, misunderstanding here. By '2nd slot', I meant the last slot as it is a PCIe slot. The two slots in the middle of your mobo are PCI slots (legacy). PCIe cards will not fit/work in these two slots. Your mobo is a micro-ATX so it is understandable the number of slots are limited versus a full ATX mobo.

As it is, since you do have a graphics card in the 1st slot, I am surprised you can get the read & write speeds you reported with the M.2 Adapter installed in a PCIe2.0x4 slot (the last slot). Did you use Crystal Mark or Atto to get the benchmark results you reported?

 

[The Original Ralph]

i used Anvil, AS SSD, ATTO, CrystalDiskMark and one other that escapes me right now

just ran ATTO - generally early in the morning, after 1st boot, i get near full spec results, late in the day like now, results degrade some - i suspect it has to do with the ssd's temperatures, but i'm not absolutely sure

and it appears i mis-spoke, it is a PCIe 2.0 x4

 

[ThomasLeong]

That's why I am surprised you managed to achieve full spec speed via PCIe 2.0x4 when the Samsung XP941 is rated for PCIe 3.0x4. The throughput for PCIe 2.0 is about half that for PCIe 3.0 given the same number of lanes. Unless, I have misread the Samsung rated specs, or it has been mis-published and the specs are actually rated for PCIe 2.0x4...or the Asus spec for that 2nd PCIe x16 slot has been wrongly published. Rare. But there is a way to check...think it is with GPUid...what is the lane count for the graphics card with the M.2 Adapter occupying that last slot? Since the LGA1150 cpu only has 16 PCIe 3.0 lanes, it should go x16 for one slot occupied, and x8/x8 or x8/x4 if that last slot takes its lanes from the cpu and not the pch (motherboard) as published. As aforesaid, it is rare/highly unlikely the manufacturer is wrong with their mobo's lane assignments.

I'll have to try my Samsung 512GB SM951 mounted to an Asus M.2 PCIe Adapter I have in a PCIe2.0 x4 lane of my ASRock Z97 Extreme6 mobo to see if I get full rated spec speed which is about 2150MB/s read. I doubt it...but worth a try to know for sure.

 

[The Original Ralph]

"....when the Samsung XP941 is rated for PCIe 3.0x4 .....".

I'm pretty sure the xp941 is PCIe 2.0 x4 - i just grabbed the first two hits on google, anandtech sez PCIe 2 x4 http://www.anandtech.com/show/8430/pcie-ssd-faceoff-samsung-xp941-128gb-256gb-and-ocz-revodrive-350-480gb-reviewed


and newegg's descript sez PCIe 2.0 x4 as well http://www.newegg.com/Product/Product.aspx?Item=N82E16820147349

that's why i mentioned above that when the 950 PRO comes in, i'll have to decide if i want to yank the video card - i will be trying it in the 2nd PCIe slot first, to see what performance loss i suffer - a review that i read indicated there wouldn't be any real transfer speed difference between PCI 2.0 & 3.0 - i'm not computer literate enough to debate it so i'll just test and see

 

[ThomasLeong]

You are dead right! Somewhere stuck in mind, the XP941 was PCIe Gen3x4, rather than Gen2x4. Now I'll have to crack it open, drain the muck out, and refill it with the correct facts. Thanks! This has been a fruitful discussion for me.

So, Arthur_S, if you have been following so far, The Samsung XP941 is fine in your setup using the last slot with a M.2 PCIe Adapter (regardless whether such Adapter is PCIe 3.0x4 or PCIe2.0x4). However, you will not get the speeds you have been reading/expecting with the Samsung SM951 or the latest 950 Pro in M.2 factor as these are PCIe 3.0x4. My apologies for the initial misconception.

 

[The Original Ralph]

WHAT nags at me is whether ultimately i'll have to upgrade the motherboard in order to keep a video card

I've also thought about keeping it at the PCIe 2.0 level and just picking up another xp941 - if only we saw pricing down to where it should be for first gen technology

 

[ThomasLeong]

With that motherboard, you have no choice if you want full speed from a M.2 950Pro.

Reason for another XP941? RAID? Your motherboard won't allow it per se. You would need a dual M.2 PCIe Adapter card which would be the cheapest route to RAID for your current setup.