New system build - AHCI or RST Premium? I'm confused!

[alex_ncfc]

Hi all,

First of all, I've kind of lost touch a bit with tech in recent years, so this is all new to me.

I just put together a new system with an M.2 drive (a 1TB Western Digital SSD) and I've gone to install the Intel Rapid Storage Technology drivers (as I noticed that in Device Manager my drive controller was just a "Standard AHCI Controller", which is never ideal for best performance)

Now the install program for Intel RST is asking me if I want to switch the system SATA controller to Intel RST Premium Mode, or if I want to stay on AHCI.

I have no clue what to do here - I saw some BIOS options (my board is an MSI Z490) for something about M.2 Genie which mentioned "Premium" in the help, but I don't actually know what it does. If I leave it on AHCI will I be missing out on anything performance-wise? It mentions that the RST Premium is "recommended" but also keeps mentioning RAID wherever I go to try and read more about this, and I do not use RAID.

Thanks for any advice!

[n_scott_pearson]

Do you plan to use RAID?

Do you plan to use an Optane Memory module to accelerate the performance of a SATA HDD?

Do you plan to use an Optane SSD?

If the answer to all three of these questions is No, then you do not need to enable or install RST at all. Once upon a time, the Intel Storage driver in RST would get you slightly better performance than the  Storage driver that was provided with Windows 7. In fact, with Windows 10, the performance of the Storage drivers is on par and there is no advantage to using RST at all (well, unless the answer to one of those questions had been Yes).

Now, that was a discussion related to SATA technology. When it comes to NVMe technology, the performance is pretty much the same. Now, everyone gets excited about using RAID0 with two M.2 NVMe SSDs to maximize the throughput. I don't think it is worth it. Let me explain. In order for RST to support RAID operations with two M.2 NVMe SSDs, the PCIe lanes that are used to support the two M.2 NVMe SSDs must be downstream of the chipset (the PCH component). Why? Because RST is implemented within the PCH. Let's do the math:

• The DMI bus that connects the PCH to the CPU has a throughput of 8 GT/s or 3.93 GB/s.
• The PCIe x4 connection of a single M.2 NVMe/PCIe connector is 8 GT/s or 3.93 GB/s.
• Wait, we don't need to do any math; the numbers are the same!

So what happens when you connect two of these drives and use RAID between them? Do you get any better throughput? Well, yes, you get a bit because of the interleaving, but you never get anywhere near the doubling that everyone is excited about. Bottom line, a non-starter for me.

BTW, I do hope that that was a M.2 NVMe drive that you purchased. Using a M.2 SATA drive is a waste of a good M.2 connector.

...S

[alex_ncfc]

@n_scott_pearson 

Thanks for that informative reply.

The answer to your 3 initial questions is no. I certainly have no intentions of using RAID - I have to be honest, I still don't fully understand RAID or what it does, which makes me even less likely to want to use it!

As for the Optane stuff, I have heard a lot about it in recent years, mainly when I was having a look around laptops 2 years ago. I'm guessing to make use of it, like you say you need an Optane module or SSD. I'm guessing the Western Digital M.2 1TB SSD I bought is not one of those?! (and to answer your final point, yes it is an NVMe drive thankfully - I actually wasn't aware that there are SATA M.2 drives)

I did install the RST in the end and opted to "Stay with AHCI" - is there any way to see if I am getting the best out of my NVMe drive?

Thanks again

[n_scott_pearson]

Yea, M.2 Type B and M.2 Type M sockets can have support for connecting a SSD to either 2/4 PCIe lanes or to a PCH SATA lane. For more information regarding M.2, start with https://en.wikipedia.org/wiki/M.2.

For an introduction to Intel Optane Memory, start with this page: Intel Optane Memory.

Optane Memory modules and Optane Memory M10 modules are used to accelerate the performance of a SATA-based SSD/HDD through the implementation of a high-speed PCIe/NVMe-based cache memory. The module itself resides in a M.2 Type M PCIe/NVMe socket and can accelerate the performance of a SATA-based device, be it a SSD in a M.2 Type B/M socket or a SSD or HDD connected to another of the PCH's SATA lanes. For more information, go on to the Intel Optane Memory M10 Brief.

Optane Memory H10 SSDs are a hybrid M.2 device that contains both an Optane Memory module and a standard SSD module. The high-performance Optane Memory module is used to accelerate the performance of the medium-performance SSD module, all in the same package. For more information, go on to the Intel Optane Memory H10 with Solid State Storage Brief.

Hope this helps,

...S