Thermal Performance Analysis

Before we start talking about the actual numbers obtained in an AMD platform we have to point out that the diagrams were built using the results taken from two thermal diodes: PWM (the thermal diode located next to the processor socket on the mainboard) and CPU (built-in processor thermal diode).

So, first come the results taken from the PWM diode on AMD platform built around ABIT AN8 SLI mainboard:

* - the fan rotation speeds are taken not from the specification list, but are calculated as the average rpm value according to S&M measurements.

On the left-hand side you can see the results from the closed system case, and on the right-hand side – from an open stand. Note that the results for Zalman CNPS9500 LED cooler are given not only for the maximum fan rotation speed of 2940rpm, but also for the medium rotation speed of 2050rpm, which was determined as an audible border between the noisy and quiet operation. As for the minimal rotation speed, we decided not to include the results for this mode.

So, how do the new coolers cope with the overclocked processor? Firstly, I have to stress that our today’s hero from Arctic Cooling coped well with this task. Also, both Arctic Cooling models, Freezer 64 Pro and Freezer 7 Pro generate quite little noise and the bearing sounds quite tolerably, unlike many other bearings that produce very unpleasant noise.

As for the Thermaltake Big Typhoon and Zalman ZNPS9500 LED, which have become very popular among computer users these days, provide about the same thermal performance at a comparable level of generated noise. In an open stand, Zalman cooler appears 6^o C more efficient, while Thermaltake cooler improves the thermal conditions by only 3^o C. I have to say though that we reinstalled Thermaltake Big Typhoon three times before we managed to obtain this result.

Nevertheless, everything we have just said has been based on the results reported by the mainboard diode. Now let’s take a look at the results obtained from the built-in processor thermal diode:

Except for the results of Zalman CNPS9500 LED, the situation remains the same. Only the gaps between the results grew somewhat smaller this time. As for the results of the Zalman cooler, it is probably the poor contact between the cooler foot and the processor heat-spreader that are to blame for the failure here. Yes, the thermal paste footprint on the cooler foot was very even, but it seems to be not enough this time for efficient heat dissipation. Unfortunately, we couldn’t eliminate the problem neither by reinstalling the cooler, nor by removing the thermal paste completely and putting a new layer on. The remarkable thing though, is that with Zalman CNPS9500 LED cooler the CPU was working stably at the frequency of 2800MHz and 1.675V Vcore, which are the maximum supported values for this type of CPU with the air cooling system. So, it would be really interesting to see what our heroes will be able to do when we install it onto an overclocked Pentium 4 processor working at 4GHz.

The diagram was built only from the results reported by the thermal diode built into the CPU. The results are actually quite interesting. Arctic Cooling Freezer 7 Pro looks very good on an open stand, however, in a closed stand its results appeared less impressive. However, despite this fact, even when our overclocked CPU temperature reached 70^o C it wouldn’t throttle and continued running at its full power. Here I would only like to say that the leadership on the Intel platform still rests with Zalman CNPS9500 LED cooling solution.