I chose that overclocking method, too, and increased the multiplier to 14x, keeping the system stable. Trying to get some more megahertz by increasing the frequency of the clock generator, I found the system losing its stability, so the highest clock rate of the Athlon 64 FX-55 without any special cooling methods was 2.8GHz in my tests.

So, the Athlon 64 FX-55 has had a smaller relative frequency gain than the Athlon 64 4000+ (7.7% only), but it reached a 150MHz higher maximum frequency. This result suggests a better overclockability of the Athlon 64 FX-55, which is manufactured with a special 130nm technology with SOI and strained silicon, in comparison with the Athlon 4000+. Owners of the Athlon 64 FX-55 will be able to achieve higher frequencies, and this may become another argument in favor of the “premium” nature of this series.

Now, I want to add a few words on the thermal behavior of the new processors, both at their normal frequency and at overclocking. Using the same cooler from AVC, I got the following CPU temperature data (Cool’n’Quiet was disabled during the tests):

To heat the CPU up in this test I used a specialized S&M utility, which is evidently the best program for testing the thermal behavior of AMD’s processors and checking their stability, for today. This utility can also warm up the memory modules and test them for any errors.

We are going to use this program in the future, too. It is free for download from here.

As for the results proper, the temperatures of the two tested processors don’t practically differ, so a larger cache doesn’t greatly increase the heat dissipation, if at all. Overclocking has a much harder effect on the temperature. For example, the 2.6GHz Athlon 64 FX-55 is very hot, just like the overclocked Athlon 64 4000+. The temperature of the overclocked Athlon 64 FX-55 looks just frightening, and quite naturally so: the higher heat dissipation during overclocking is due to the frequency growth as well as to the increased core voltage.

Finishing this temperature-related discussion, I want to remind you that AMD is offering its Cool’n’Quiet technology to reduce the heat dissipation of its processors under small loads. This technology is realized through a CPU driver, which drops the CPU voltage and the multiplier coefficient when necessary. Cool’n’Quiet is supported in both Athlon 64 4000+ and Athlon 64 FX-55 processor models.