I replaced my RAM because the sticks went bad. For now I put back in the 16gb sticks that came with my desktop, but I plan on going back to 32 once I can get the sticks in. The machine is a Dell Inspiron 5676 that I have been happily dual booting for over a year ( with Ubuntu as my primary OS for development, but using Windows for some gaming and software for the kids' toys) Once I got the new sticks in, Windows works perfectly. Ubuntu gets partway through the boot and then the monitor off HDMI, which is my primary display and sound, says "no input." Both monitors are plugged into the same Radeon card, and there is no on-board video. The card must work, since it works fro GRUB and Windows 10.
The Ubuntu side boots and runs fine, it just won't use the HDMI port. ( I did try adding nomodeset, but that prevented it from booting at all)
I had a similar situation a few months ago. I upgraded to 64GB from 32GB. I changed nothing in the BIOS. I could not boot into Ubuntu at all (I do not have Windows).
After a bit (lot?) of hair pulling, I went into the BIOS and changed the ram frequency down (from 3200 to 2666). Computer booted perfectly.
I do not know if you can change things like ram frequency on your Dell, but that might be a good place to start.
When I swapped the RAM it changed some of the BIOS options (legacy boot, tpm etc) which disabled the HDMI drivers. Video is working fine now. (Audio isn't, but I'll post a separate question if I need to)