You'll probably need to remove the cooler.

Yes, you’ll need to take the cooler off. In a mini-ITX build with a big air cooler that hangs over the RAM slots, there’s usually no way to access the clips or even slide the RAM sticks in. No special tools required — just a Phillips screwdriver and some thermal paste to reapply. But it’s more than a five-minute job.

The real pain is that removing the cooler means cleaning off old paste, putting on new paste, and reseating the cooler. If you have a tower cooler that’s bolted through a backplate, you might also need to pull the motherboard out or at least get your hand behind it. Mini-ITX cases are tight, so even that step can take 15–20 minutes.

If you haven’t bought the RAM yet, check your cooler’s clearance. Low-profile RAM (without tall heat spreaders) sometimes fits under a big overhang. But if the cooler physically blocks the slot, there’s no workaround — you have to take it off.

Future you will thank past you for buying RAM that fits without disassembling the whole damn thing.