XPS 8930, adding an additional SSD?

First, you do not want M.2 SATA. It looks like you already have an M.2 NVMe SSD drive on your motherboard just above that red oval. If you want another M.2 NVMe SSD drive you would need a PCIe adapter to install. The easiest thing for you would be to get a 2.5-inch SATA SSD . . . something like this  that would mount into one of those two bottom cages. You would need a SATA data cable. Consider a SATA data cable with a 90 degree connector on one end.

@Chino de Oro @ProfessorW00d (pinging manually since I forgot to make this a reply...)

I see, thank you guys for the responses, I'm learning a lot! So it seems like there are 2 options:

1. NVMe SSD such as SAMSUNG 970 EVO that I plug directly to a PCIe x4 M.2 adaptor such as GLOTRENDS M.2 PCIe NVMe 4.0 Adapter with M.2 Heatsink that I then directly plug onto the PCIe x4 port on the lower left of my image.

2. 2.5-inch SATA SSD such as Western Digital 1TB WD Blue SA510 SATA Internal Solid State Drive SSD - SATA III 6 Gb/s, 2.5"/7mm that I mount onto one of the bottom cages, potentially with a 3.5" to 2.5" cage adaptor such as from S.H.Y SPRUCES SSD Metal Mounting Bracket Kit, 2.5 to 3.5 Hard Drive Adapter which also comes with some SATA data cable to connect to one of the SATA ports I've labelled above.

Is my understanding correct? If so, I'll probably go for option 1 since it'll be faster with no data cable. (updated annotated photo below)

Yes, you got it.

Good upgrade choice too.  Don't forget to run the wizard to add new drive in Disk Management.

This is my XPS 8930  M.2 NVMe PCIe adapter is the X4 slot

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@ProfessorW00d​ Oh nice, didn't realize that the motherboard had explicit labels next to each of the slots 

@johnsonzhong_5ca752​    indeed they do . . . this is the clearest photo I have of the slot labeling

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I have a Dell XPS 8930, purchased from Costco in 2019.

Installed new SSD:  I installed a Samsung 870 EVO 2 TB SSD to replace my HHD, because I got an error on my HHD when I did a Dell Service Check on it.  Also my files had been opening verrry slowly, so there was definitely a problem on that HHD.

I thought that the SSD was not being recognized by my Dell 8930, because I did not see the drive listed as a local drive.  But it was recognized.  I did see the drive listed in Windows Device Manager (just type "Device Manager" in the Start menu search bar).

If you see the device there, you will have to go to Disk Management -- go to Administrative Tools in the Control Panel and then to "Create and format hard drive partition" (or just type "Disk Management" in the Start menu search bar). Select the drive and format it and give it a drive letter from the dropdown list.  Then go to your file manager and you should see it.

Note that I DID NOT change the BIOS setting from RAID to AHCI.

Cloning the Drive:  I used the 2TB HDD for my data, so when I installed the new 2TB SSD, I wanted to simply clone my old HDD to the new SSD drive and use it as my new drive (complexly removing the old faulty HDD from my system).  I used  “EaseUS Disk Cloning Software”, which got rave reviews on many reputable sites.  Some sites said there was a free version, but every time I tried to clone, I was prompted to pay for the software.  In the end I just paid because my data is too important to try to find a reputable free version (it cost about $20).

Updated Memory:  I updated from the orginal 16GB RAM (2 8GB memory sticks) to 32GB (2 16GB memory sticks) with a faster read speed (from 2666MHz to 3200MHz). I purchased Corsair Vengeance LPX 32GB 3200MHz DDR4. By the way, don’t be temped to put your old 2 memory sticks in the extra two slots because then all of your RAM will run at the lower speed.  You can monitor if you really need more than 32GB of RAM via the Task Manager, but if you are not running out of RAM (not likely), then you don’t need to add more.  Better to run at faster speed than have extra RAM at a lower speed just not being used.

Updated Power Supply:  The original power supply on the Dell XPS30 was only 460 Watts, which might have been an issue damaging my HDD with not enough power.  So I updated the power supply to 850Watts.  (Note that this is a recommended upgrade from Dell for the XPS 8930 and Dell sells their own 850Watt power supply).  But I installed the Corsair RM850x, which was less expensive than the one from Dell.  Note that the Corsair RM850x does not come with an optical drive cable to connect the CDROM, but I was able to buy one for $5 (a SATA 15pin to 6pin connector).

My system is sooo fast now!

Hope this is helpful for someone.  I appreciate all the great info I got from forums.

Did Option 1 work? I tried Kingston NV2 PCIe 4.0 with UGREEN PCIe Gen4 x16 to M.2 Expansion Card. After installation the PC booting significantly increased. It can still launch, but it cannot detect the SSD in Windows or BIOS. 

@SBSunny​ did you use that software to clone your OS drive, or was it a data drive? I'm looking to replace my OS NVMe from 256gb to 2TB and don't want to reinstall the OS, drivers, apps, etc. Thanks!