Is M.2 SSD Sata III = M.2 SSD Pcie?

My question is that Sata 3 has already good Bandwidth,i mean, it is not limiting the SSD right?
but i see some new M.2 Pcie SSD reach 1.3GB/sec and some even more (2.5GB/sec)

So why are the Sata 3 ssd's have slow speed?

and if i want to buy an Pcie SSD for a Laptop with M.2 pcie x2/x4 port, what would be the best buy ?
Or should i wait for more fast Pcie SSD's to release?

And just because an M.2 SSD has Pcie interface , it doesn't mean it has that super speed right?

 

Newer SSDs are capable of speeds faster than SATA III. Note your motherboard also needs enough pcie lanes connected to achieve that speed, and nvme support - you won't find these in current notebooks so don't bother looking.


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I think this notebook has one slot , right?
XOTIC PC | Sager NP8651 (Clevo P650SE) - 15.6" Gaming Notebook

And this article has some good info on the M.2 Slot
Overview of M.2 SSDs - Puget Custom Computers

And many people are saying that the speed difference will only be visible when working with huge files,
Sooo i guess i will go for the Transcend ,it has double the space for same price compared to other M.2 SSD's with normal SSD speeds
Amazon.com: Transcend 256 GB SATA III 6Gb/s MTS800 80 mm M.2 SSD Solid State Drive TS256GMTS800: Computers & Accessories

 

1) Actually, you are incorrect. Sata-3 *IS* limiting the maximum speed of the SSDs. SATA-3 has a theoretical bandwidth limit of 6Gbps. And we see that most SATA-3 SSDs max that out, with a maximum read/write rate of about 550 MBps.
2) An M.2 SSD connects through the PCIe interface, and not SATA-3. Therefore, it is capable of faster speeds than the 550 MBps limit you see on SATA-3.


However, keep in mind that maximum transfer speed DOES NOT MATTER. for two reasons:

1) Maximum transfer speeds only occur when doing sequential read/write patterns. 95% of the data access patterns you see when using your computer will be random read/writes that will be far slower than the SATA-3 limit of 550 MBps. That means that you will almost never see a real-world difference between SATA-3 or M.2 SSDs when using your computer for "typical" tasks.

2) Maximum transfer speeds only matter when you can read data FROM (or write data TO) some target location that can also sustain those speeds. And very rarely will you ever find a situation when you can actually read / write data above 550MBps speeds.

Again, maximum transfer speed DOES NOT MATTER.. Do not base a purchasing decision on maximum transfer speed, because you will never see the benefit of that in real-world usage. When dealing with SSDs on laptops, the far more important factors to consider are price, storage capacity, and maximum total storage options for the laptop. Ideally, you want to buy a 256GB or 512GB M.2 SSD for your laptop so that you can put a slow mechanical HDD in the 2.5" SATA slot for bulk storage of media.

 

And what is its fastest speed?

According to wikipedia we have that:

And, again, from wikipedia we have that:

So, am I right to assume that the fastest speed for a M.2 SSD is 985 MB/s?

 

Wait a second. If M.2 SSD's connect through pcie, does that mean that with an M.2 to mpcie adapter, one could install an SSD into a mpcie slot that doesn't have sata?

 

Yup.
M2MP1 M.2 (NGFF) to mPCIe (PCIe+USB) Adapter

 

You will need HM97/QM97 chipset or third party PCIe controller on the motherboard to be able to get speeds past SATA3 with a M2 SSD.
HM97/QM97 is chipset for Broadwell so if you have Haswell in your notebook, you are bound by SATA3 speeds. Everything goes through the SATA controller.

Very few notebooks have third party PCIe controllers.
You can use M2 SSDs rated to 3GB/s etc on a standard M2 slot, but you will get tops 600MB/s.

 

usually the space for mPcie slot is less, and if you plan to have a M.2 SSD ,even with 60mm M.2 SSD you might not be able to have the space for the SSD as the Adapter takes some space

Edit : I might be wrong.

 

I was a little wrong there..

Taking into account that:

It should be roughly 985*4 MB/s = 3940 MB/s, a little less than 4 GB/s.

 

..then again, we don't actually know how those lanes will be allocated, how many will be free on the bus (either internally or externally - e.g., the normal components could perhaps allow dynamic allocation, and the "standard" would still be fulfilled if there's a minimum requirement, that sort of thing), or if the memory controller (where the information suddenly has to pass through a scheduler programmed for PCIe, instead of as DMA, and so on) can actually handle anything nearby what is theoretically possible.

That's likely why no one has actually put any four-lane drives up on the release-calendar yet as well. That it would require some sort of rework of how the drive cache works (it'd have to be comically fast, and able to structure transfers in batches, for example), and then have that work in conjunction with a new PCIe scheduler. Which probably again would then have to rely on the OS allowing enough data to predict these batch-transfers from.

In other words - it's an unrealizable project on the consumer market, (and every overpaid IT-consultant's shaking wet dream).

 

9 series chipset are bound to 1GB/s. Thats all it supports.

There are motherboards around that supports 2GB/s and upwards, but that is third party controllers that connects to CPU lanes and get lanes from there. I think they are called Ultra M2