Please note that results in reviews might show different results as many tests are conducted in open test bench configurations outside a chassis, which allows a better supply of fresh air and thus allows the coolers to keep lower temperatures than in a real-world setup inside a chassis.
Secondly, processors emitting heat-loads of 180-250W or even more (with Turbo Boost) create more challenges for case ventilation than lower power mainstream CPUs as it is very difficult to remove so much heat from the chassis. For best performance, it is crucial that sufficient amount of fresh air can enter the chassis and that warm air leaves the chassis as fast as possible.
Internal testing at Noctua has shown that many PC cases are rather restrictive when it comes to air intake and exhaust due to dampening materials, doors, covers or a rather closed design approach in general. Increasing the number of system fans can help to a certain degree, but will not provide much improvement if intakes and outlets are too resistive. The best cooling results are to be expected from cases which use a rather open approach (e.g. mesh walls and intakes). Unfortunately, Noctua cannot provide detailed recommendations for individual system configurations, as there are too many options and variables available to give general recommendations. Please refer to various general case cooling guidelines for information on how to set up the airflow inside your case.
Modern AMD and Intel CPUs
Modern Intel and AMD CPUs have a different behaviour when it comes to temperature. In the past, CPUs had a higher lightweight boost algorithm, this meant that there is more manual overclocking headroom. Today, CPUs aggressively use their temperature and power headroom to achieve high clock speeds. This means they quickly reach their maximum safe temperature (85-100°C).
Hence, our compatibility centre might show higher turbo/overclocking headroom for the NH-U12A over the NH-L9i, although both of them may have the CPU at its maximum safe temperature. This is because temperature alone is not a performance metric. The clock speeds at which the CPU operates is equally important.