This system is too old to support either M.2 SATA or M.2 NVMe.  If you want an SSD, you need a 2.5" SATA SSD.

There is a couple of spots on the motherboard for something? One spot says: PCIe and the other says msata-1

PCIe slots will hold PCIe cards - not M.2.  The system is not set up (does not have compatible firmware) for booting from PCIe SSDs.

The mSATA slot will take an SSD - but you will be capacity-limited on these (they're fading fast from the market and were never made in high-capacity drives).  If your're OK with paying more for a 512 G mSATA (and note that mSATA is NOT the now common M.2 format) drive, yes - you can use one of these, but you'll get far more for your money (and probably better performance as well) from a standard 2.5" SATA solid state drive.

The ability to boot from NVMe SSDs arrived in late 2015 and came into force during 2016.  Your system is much older than that.

Just to add to ejn63 great comments.

Dell used the top PCIE_MINICARD white connector for our wireless card.

The bottom MSATA1 white connector was used with optional mSATA drives with capacity of 32GB to 512GB. Below are the Dell part numbers for the 512GB mSATA cards =
Y012F Samsung PM871
7KDNC Samsung SM841
295GT Samsung SM841N
099H4 Liteon L9M
F2T2Y Liteon V2M
VGXRN Hynix SC300
M196W Micron M550

Hello Chris,

You mentioned below that the original XPS 8700 mSATA 1 slot was meant for SSDs ranging from 32GB to 512GB.

I'm interested to add the following mSATA SSD to my old XPS 8700:

SAMSUNG 860 EVO Series mSATA 1TB SATA III V-NAND 3-bit MLC Internal Solid State Drive (SSD) MZ-M6E1T0BW

https://www.newegg.com/Product/Product.aspx?Item=N82E16820147687&cm_re=msata_ssd-_-20-147-687-_-Product

Would this 1TB mSATA III SSD work with XPS MoBo ? Or Am I limited to the 512GB version ?

In all cases, the mSATA complies with SATA III speed. Will a SATA III SSD work with the SATA I interface on the XPS 8700 ?

Thanks a lot for the advise !

Would this 1TB mSATA III SSD work with XPS MoBo ?
* Unknown. We never tested one.

Will a SATA III SSD work with the SATA I interface on the XPS 8700 ?
* SATA 3 SSD should be backward compatible to SATA 1. But why spend the money to just slow it down?

Why mess with msata and less than sata III hdd when you could have the current stuff for a few more bucks. Don't future proof it but don't drag it backwards...…….

Thanks for the feedback !

After so many comments, it really seems mSATA is not the way to go.

M.2 SATA SSDs do not fit on the XPS 8700 MoBo.

The only SATA III solution left is the 2.5" form-factor.

The question is, where am I going to place it ?

Does it go on the same place as the HDDs ? Connected to the same data & power connectors ?

Thanks again in advance.

Nothing wrong with 2.5" ssd's, and you can slap em' anywhere with double sided tape and data and power cords to reach. No difference between the M.2 sata drive and the 2.5" other than one needs cords.

NEITHER SLOT is M2

MSATA is NOT M2.

Motherboard

M2 2280 IS NOT MSATA

There is an "mSATA 1" which can accommodate up to a 1TB mSATA drive.

https://youtu.be/oUl7OzfiuXs

This is how to install an mSATA onto a DELL r17 5720, although it's the same for any other motherboard with an "mSATA 1" slot like this. The pins are the same. It's a short form factor.

https://www.parts-people.com/index.php?action=item&id=26029

This is the drive, although with a little searching, there may still be 1TB drives out there in this form factor.

https://www.dell.com/community/Laptops-General-Read-Only/mSATA-SSD-as-Bootable-Drive-Inspiron-17R-5720/td-p/4092181

This will explain the process of getting it to be a bootable drive.

For the record, I am a retired computer science professor and technician of over 20 years. There is no such thing as a bad question. I applaud you for wanting to get the most out of your equipment.

These upgrades add useful life to older gear, and in many cases keeps it not just functional, but indeed, quite useful!

I just bought one of these for my XPS 8500: https://smile.amazon.com/gp/product/B07C3YY66G/

were you able to configure it to boot to that?  thinking about doing the same.  Anything I should know about?

KINGSTON Digital SUV500MS/480G

Booting Msata regardless of from whom requires AHCI setting.

F6 Mass Storage Drivers are Required for advanced format drives.

Most all drives made after 2011 whether SSD or HDD are Advanced Format AHCI drives.

The one TB I can find is

https://www.amazon.com/Samsung-V-NAND-Solid-State-MZ-M5E1T0/dp/B00TGIVRYU