Noctua NH-U12P: Top Performance AND Silence

Overclocking and Performance Scaling

With outstanding performance at stock speed, we pushed the Noctua NH-U12P in our performance scaling tests to see if this air-cooler delivers similarly impressive performance when pushed hard in overclocking. As cooling solutions do a better job of keeping the CPU at a lower temperature, it is reasonable to expect the overclocking capabilities of the CPU will increase. In each test of a cooler, we measure the highest stable overclock of a standard X6800 processor under the following conditions:

CPU Multiplier: 11x (Stock 11x)
CPU Strap: 266 (stock) or 333 (overclocked)
CPU voltage: 1.5875V at max overclock
NB Voltage: 1.70V
FSB Voltage: 1.40V
SB Voltage: 1.20V

Memory is set to Auto timings on the P35. This removes memory as any kind of impediment to the maximum stable overclock. As FSB is raised the linked memory speed increases in proportion. For this reason, we maintain memory speed as close as possible to CPU strap settings to prevent memory becoming an issue in CPU testing. This means 3.33GHz uses a 333 strap and runs 10x333, 3.73GHz uses a 333 strap and runs 11x339, and 3.90GHz is a 333 strap and 354x11. The stock speed test is a 266 strap and 11x266. We may move in the future to a 3.0GHz stock speed with a 333 strap and 9x333 settings for complete consistency, but since we are not measuring raw computer performance in our cooling benchmarking this becomes a moot point. The same processor is used in all cooling tests to ensure comparable results.

The stock single-fan Noctua reaches 3.91GHz in our overclocking tests, a result exceeded only by our top Thermalright Ultra-120 eXtreme. Even more impressive is the performance achieved when we use two NF-12P fans in a push-pull arrangement, with a top overclock of 3.94GHz. This matches the Thermalright Ultra120 eXtreme as the best air-cooler ever tested at AnandTech.

This superb overclocking performance combines with silent operation, with noise floors below our quiet system level. Noctua appears to have developed a cooler that combines top performance with incredibly low system noise. With the Noctua kit and the NF-P12 fan, you no longer have to choose between top performance or lowest noise. The NH-U12P can give you both - even if you add a second NF-12P fan in push-pull for ultimate cooling.

Performance Scaling

Performance scaling charts for the Noctua NH-U12P use a scale with zero on the bottom and 75C on the top. Keep in mind that the lower line is the best performance in this presentation of the data - lower temperatures represent better performance.

The NH-U12P performance scaling at idle is impressive. It is all but a mirror image of the superb Thermalright Ultra-120 eXtreme running a Scythe S-FLEX fan. When we add a second NF-P12 fan in a push-pull setup, the Noctua is in a class by itself. Temperatures drop another 3C or so and the performance curve is all but flat from 3.73GHz to the top speed of 3.94GHz. If you recall from past test results, a flat curve (shallower slope) indicates a cooler is still in its effective cooling range.

Next, we compare cooling efficiency of the Noctua NH-U12P under load conditions to the retail HSF and other recently retested CPU coolers. Load testing can be very revealing of a cooler's efficiency. Again, we like to see a relatively flat line, which often means we are at the limits of our CPU rather than the coolers. A line with a steep slope indicates a cooler is nearing the end of its ability to cool effectively.

Under load test conditions, the stock NH-U12P again matches the top Thermalright. The single-fan NH-U12P tops out at 3.91GHz while the Ultra-120 eXtreme continues on to 3.94GHz. Temperatures under load at tested speeds are all but the same in faster speeds, while at lower speeds the NH-U12P is actually a bit better performer. These results are very impressive.

Adding a second fan in push-pull again creates a new performance class with the Noctua NH-U12P. Cooling on average is 2C to 3C better than our previous top performer. That may sound like a small amount, but in cooling this difference is significant. With two fans, the Noctua extends to 3.94GHz and sets a new record for best cooling performance at the highest speed we have been able to achieve in air-cooling with this CPU.