Your current 12th-gen motherboard likely won't support both.

Probably not. Intel’s 12th-gen CPUs (Alder Lake) do support both DDR4 and DDR5, but motherboard manufacturers almost always build a board for one or the other. A few early “dual-channel” DDR4/DDR5 boards exist (like some Asus Z690 and Gigabyte Z690 models), but they’re rare and usually require specific BIOS support.

If you bought a standard Z690 or B660 board, it’s almost certainly DDR4-only or DDR5-only. There’s no magic switch to make it work. You’d need to check the exact model number. If it’s a DDR4 board (most common for 12th-gen builds), you’re stuck with DDR4.

Upgrading to DDR5 means a new motherboard. And while you’re at it, you might want to consider a 13th- or 14th-gen CPU, since the new board will support those anyway. But for just the memory jump? The performance gain from DDR4 to DDR5 alone isn’t huge for most games and tasks—don’t feel pressured to upgrade unless you’re doing heavy production work.

Bottom line: Check your board’s RAM slots. If they have a notch in the middle (DDR4), you can’t use DDR5. If they’re keyed differently (DDR5), you’ve already got it. No board does both out of the box.