I posted your question to my Claude AI tool and got this response. You may want to try this. I hope it helps.

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That's a classic Dell gotcha, and I ran down the specifics so you can point the original poster in the right direction.

What's going on: RST (Intel Rapid Storage Technology) is a translator that sits between the hard drive and the operating system. Dell turns it on by default on many laptops so Windows gets a speed boost. The catch is that Linux doesn't speak that particular dialect. MX Linux's installer notices the disk looks like it belongs to this translator setup and simply refuses to touch the whole thing (hence the greyed-out button), while Linux Mint is a bit more polite about it and just tells you straight out to turn RST off.

Finding the setting on a Precision 7710: This model uses Dell's older-style setup screen, and Dell's own support documentation confirms the location for machines of this vintage.

1. Restart the laptop and tap F2 repeatedly right when the Dell logo appears (not F12, that opens a different one-time boot menu and won't have this option).
2. Once in System Setup, look at the list of tabs down the left side and click "System Configuration." It's easy to skim past this one while hunting through "General" or "Security" instead.
3. Inside that tab, scroll down to "SATA Operation." It's most likely set to "RAID On."
4. Change it to "AHCI."
5. Save and exit (usually F10, or a button at the bottom of the screen).

If the BIOS has been updated recently, Dell has moved this on some newer firmware to a tab simply called "Storage," under an option named "SATA/NVMe Operation," so it's worth checking there too if "System Configuration" comes up empty.

One thing worth mentioning to the poster: if there's still a working Windows installation on that same drive, flipping to AHCI can make Windows refuse to boot afterward, since it loaded RAID-specific drivers at install time. Since they're planning to wipe the disk for Mint or MX Linux anyway, that's probably a non-issue, but worth a heads-up in case anyone reading the thread wants to keep dual boot alive.

Once AHCI is selected, both installers should stop treating the disk like a mysterious RAID array being guarded by an overly cautious tour guide, and the "entire disk" option should light back up.

Sources:

• Dell: Recommended BIOS Settings for your Linux System
• Dell: Latitude Systems Shipped with Default RAID On Mode from the Factory