XPS 8500, how to make a mSATA drive a boot drive?

the mSATA (default Dell oem 32GB) was meant as a cache device along with regular sata hdd set up in Intel rapid storage.

installation is straightforward.  If you still have the screw for the mSATA slot, simply install the mSATA and fasten it with the screw.

in order to use the mSATA as a separate boot drive (despite its small size), first enter bios to change sata operation from RAID to AHCI, save changes, exit bios.  You ought to have cmos battery replaced w a new one and cmos settings cleared by mobo jumper as a prerequisite maintenance step.

next before you install OS on the small mSATA, temporarily uninstall the regular sata HDD.  Then do a clean install of Win 10 using MS installation media (USB preferred over DVD).

when that is done and Win 10 can run smoothly from mSATA, reinstall the regular sata HDD and use it as D: drive (wipe it by deleting all existing partitions and create new single volume)

Note although Win 11 can also be installed in 8500 by using some tricks, the 32 GB oem mSATA is too small to accommodate the size of Win 11.  you can upgrade to 128 GB mSATA.

Thank you so much for the response. I have a 256 GB mSATA on the way that I will use. I already have a 1TB HDD in it, which is about a year and a half old, and I was also thinking of swapping that out. I don't mean to sound dull, but is the CMOS battery the coin battery on the motherboard? And I don't know what a mobo jumper is. And when you say uninstall the HDD do you mean unplug it or wipe the drive?

cmos battery is the coin battery

look for a jumper where it says RTCRST.  you do not have to reset if everything works now

uninstall hdd can mean just unplug sata data cable from it

Dell doesn't support Win 10 on XPS 8500. Even if you can find all the right drivers for your hardware to run Win 10, is this mSATA upgrade worth the money?

mSATA is old technology so the new mSATA drive won't be usable if/when you decide to replace this PC.

And, Microsoft's support for Win 10 ends in Oct of this year and there won't be any additional security updates, etc, unless you're willing to pay a subscription fee to Microsoft. And who knows how long they'll continue offering this subscription?

Your PC, your money, your decisions...

It's very simple.  After installing an mSATA drive, just performing Windows installation and treat the mSATA like any other drive.  Windows boot manager will be auto setup to select and boot the mSATA drive without the need for BIOS setup.

Since your system has been activated for Windows 10 pro digital license, you can perform a clean installation of Windows 11 and the new license will be activated.  Search around and select bypass option of your choice to install Windows 11 on unsupported hardware.  

After Windows installation is complete, you need to install the chipset driver and HECI driver.  Run Windows updates and all remaining drivers will be installed automatically.

@deerpark243 - Even if you can run Win 11, IMO, a better option would be to replace the existing HDD with a 2.5" SATA SSD rather an installing a larger mSATA SSD as the boot drive.  You could keep the 32-GB mSATA drive as a (small) storage space.

At least a SATA SSD should still be usable when installed in a new PC, but the mSATA SSD is a dead-end because new PCs don't have mSATA ports on their motherboards.

Besides, Microsoft just quietly removed instructions for work-arounds to run Win 11 on "unsupported" hardware.  So at what point are they going to completely deny any/all Win 11 updates for hardware that's not on their "supported" list? Probably some time after Oct'2025, when support for Win 10 ends...

Like I said: your PC, your money, your decisions...

The 256 GB MSATA drive came in. I'm running 32GB of RAM with an NVIDIA GeForceGTX 1050 Ti graphics card, so I have already invested a lot of money into this PC, and I like it; the SATA drive takes about 11 minutes to fully boot up. I will install the  MSATA memory, but I'm still not quite sure about the sequence after I install the MSATA. And I don't want to sound dull, but I'm trying to make this process go as smoothly as possible. So, after I install the MSATA, I can go into the BIOS and change the booting sequence to having the MSATA as the primary boot drive, and while I am in there, unplug the SATA drive and boot up the MSATA with Windows 10 pro on a USB and it then it should install correctly? Then plug in the SATA drive and boot it up by changing the boot sequence the wipe the drive clean, then change the boot sequence to the MSATA, and use the SATA drive as storage. Is that how I do it ( and change the SATA drive letter to "D" drive)?

@Chino de Oro​

Each questions can be explained with clearer reasoning:

*  When installing Windows, the installer would create four partitions on the boot drive.  Therefore, we want to delete all of the existing partitions on the intended boot drive so that the installer can create new partitions properly.  Removing all data drives can ensure that they don't get delete by accident.

*  If your internal drive has data and Windows 10 pro on it, consider that was your old boot drive.  I suggested to leave it connected and delete all the partitions during Windows installation.  All data from that old boot drive was supposedly backup external routinely and prior to the installation process.

*  Assuming your mSATA drive has nothing on it, make sure that drive number is one unallocated space. 

*  Windows 10 pro on your USB drive would not automatically downloading onto the mSATA drive.  I said when installing Windows 10 pro on mSATA drive, it would create a Windows boot partition on it and from each of the next boot processes, BIOS settings with Windows Boot Manager will automatically find that boot partition and will boot the mSATA.  Users do not need to set the mSATA as the primary boot.

I suggest that you need to review the Windows installation process and raise any question you have before actually working on it to prevent mistake.  Also, verify that you have all your data already backup outside of the computer.  Any connected drive would be deleted during installation (assuming only one old boot drive).

No question is dull, you are welcome to post any question.  I will assist with what I can offer.