CPU Temperatures at 3GHz
To compare the performance of these three coolers, we graphed a log of Everest's CPU temperature probe over a computing session. Before starting the log, I let the system warm up to a stable idle temperature. Next, I let the system idle for 15 minutes before turning on Prime 95's maximum heat test for all four cores. The Prime95 load ran for 20 minutes—long enough for load temperatures to stabilize with each cooler. Finally, I halted the Prime95 test, returning the system to idle, and let Everest log CPU temperatures for another 25 minutes.

At stock speeds, all three coolers perform almost identically, with the Domino managing a CPU temperature one degree lower than the rest under load. More interesting is the shape of each temperature curve around when we start and stop our load. The NH-U12P and Domino cool our test system's processor at a quicker pace than the H50. This suggests that the H50 could have more overall mass than the Domino or that it's simply not whisking heat away from the CPU as effectively.

Separating our data into idle, load, and cooldown temperatures, we get another look at just how closely matched these three are. The fact that all can keep a full-loaded Phenom X4 running around 43 degrees is quite impressive. How about the other part of the equation, though? These days, a heatsink doesn't just have to keep a processor cool—it has to do so quietly.

To get a feel for how much noise each setup makes, we took sound level measurements with each cooler from three locations: 12" away from the front, top, and left side of the case.

Now that's a quiet fan: even running on a full 12V, the Noctua makes less noise at idle than either of our two water coolers. The H50 is the quieter of the liquid-fueled units, and it emits a less obnoxious whine than the Domino.

Even under the strain of a fully loaded quad-core processor, the H50 doesn't run any louder than it does at idle.