G5 5590: Intel RST recommended?

You only need RST if you're doing one of the following:

- Using an actual RAID setup (on systems with multiple drive bays/slots for this)
- Using Intel Optane
- Using Intel Smart Response (older version of Optane)
- Trying to install Windows 7 onto an NVMe drive, since Windows 7 doesn't support NVMe (although installing Windows 7 on newer systems now would be problematic for other reasons too)

If you're not doing any of those things, use AHCI.  It's one less driver to deal with, and in fact it's required if you ever want to use Linux since there's no Intel RST driver for Linux.  The reason Dell uses RST is because they can standardize on that setting for every system they build for manufacturing simplicity and it will always work for what they need -- except for Linux, but Dell offers very few systems with Linux installed at the factory.  For every other scenario, they might need to load the Intel RST driver as a result, but obviously with automated manufacturing that's a pretty trivial thing to do and they're already doing that anyway for the rest of the system's hardware.

Intel RST likely won't impose a performance PENALTY -- I remember benchmarking an XPS 13 9360 with a Samsung 960 Evo in AHCI vs. RAID mode and I didn't find a significant and repeatable difference -- but again if you don't actually need what it offers, then I personally would and do use AHCI.  Just be aware that you either need to make this change prior to doing a clean install or else you need to switch this setting and THEN boot Windows into Safe Mode once so it will change the driver out.  If you make that change and then try to boot Windows normally, it will BSoD until you go through Safe Mode once or change the setting back.

Thanks for the quick reply, @jphughan . I will go with AHCI then. I don't think this laptop actually does RAID, even though there's the RAID On option under System Configuration > SATA Operation - I don't see a RAID menu (or any options) to setup a RAID array, rebuild array etc. anywhere. It seems like a misnomer. The explanation for the option is given as "RAID On = SATA is configured to support RAID mode (Intel® Rapid Restore Technology)" - seems Dell even got the name wrong there (which is presumably Intel® Rapid Recover Technology). An Optane module doesn't seem to be present on the machine (and I don't care for one) and I have no intention of installing Windows 7 (that would be a battle).

Cheers.

@pluriel  RAID isn't a misnomer and RST does in fact stand for Rapid Storage Technology, which is Intel's naming, not Dell's.  So Dell got the naming wrong if it says Restore, but it shouldn't be Recover either (those are basically the same thing anyway).  When a system actually has multiple disks installed that could be configured as a RAID virtual disk and the system is in RAID mode, then during initial boot you see an additional screen that shows you the status of your RAID virtual disk(s) you've already configured and prompts you to press some key combination to access the Intel RST configuration interface, where you can perform RAID management tasks.  You can also create RAID virtual disks using the Rapid Storage Technology application in Windows, but of course that wouldn't work if you wanted to install Windows itself onto a RAID virtual disk.  (Some laptops have more than 2 storage bays, and the RST controller is also found on some desktop systems.)  In your case, my guess is that you're not seeing that additional boot screen even in RAID mode because you have one NVMe and one SATA storage device and the RST controller doesn't support creating a RAID virtual disk with a mixture of NVMe and SATA storage (nor would you really want to).

As for Optane and Smart Response, those are quasi-RAID setups in the sense that two physical storage units are presented to the system as a single virtual disk, but it's certainly not traditional RAID.  Instead it involves using an SSD-type module as a large cache for (usually) a traditional spinning HDD.  As for Windows 7, the only reason RAID comes into play there is because AHCI exposes the raw storage interface to the OS, and Windows 7 doesn't support NVMe.  RAID mode causes the RAID controller to be active, which abstracts the physical storage interface from the OS.  In that setup, Windows 7 just sees a RAID controller, so as long as the driver for that controller is provided, then the fact that it doesn't support NVMe is irrelevant at that point because the RAID controller is handling that side of the equation.

Thanks for the correction about RAID functionality @jphughan  - there's no mention of RAID anywhere in the laptop's documentation either, which is why I thought it might be absent. Also many thanks for all the generous info. You've been most helpful.

Cheers

@pluriel  happy to help!  And thanks for the kind words.  Good luck!