How do I check if my RAM will fit under my CPU air cooler?

Check your cooler’s published “RAM clearance” spec—that’s the tallest RAM that fits under the front fan without moving it. If your RAM is taller, either buy low-profile RAM (under 32mm) or raise the front fan a few millimeters (but that adds height). Single-tower coolers usually don’t overhang RAM, so clearance isn’t an issue. Measure your RAM’s height against the cooler’s spec to be sure.