Check your cooler's clearance before buying RAM.

You need to measure or look up the clearance between your CPU cooler and the motherboard’s RAM slots, then compare with the RAM’s height.

Most air coolers have a “RAM clearance” spec in millimeters. If the cooler overhangs the slots (common with dual-tower coolers like the Noctua NH-D15 or be quiet! Dark Rock Pro), tall RAM heatsinks won’t fit under the fan. The fix: either move the fan up (which reduces case compatibility), use low-profile RAM, or check if the cooler has a cutout.

For liquid coolers (AIOs), the pump block often has the same issue—some designs are offset to avoid RAM slots, others aren’t. Look up your specific AIO model’s RAM clearance.

The simplest method: measure the gap between your current cooler’s bottom edge and the motherboard. Then check the RAM’s height spec (tall kits are usually 40-50mm; standard is ~32mm). If your gap is less than that, you’ll need low-profile RAM or a cooler adjustment.

Don’t guess. That’s how you end up with a fan resting on a heatspreader and a system that won’t boot.