Overclocking and Temperature
The Athlon 64 FX-55 and 4000+ are top-end and also the last processors AMD is making with 0.13-micron tech process, so we can’t expect them to be overclocking marvels. Considering the fact that the Athlon 64 4000+ is a remarked Athlon 64 FX-53 – and we have already investigated the overclockability of the latter well enough, it is clear that this processor will be rather bad at overclocking and will hardly reach a frequency much above 2.6GHz. The Athlon 64 FX-55, on the contrary, is a “dark horse” with its specially adjusted 0.13-micron tech process with SOI and strained silicon, so I would refrain from making any suppositions about its overclockability, especially since its regular clock rate is 2.6GHz already.
I checked out these theories and assumptions in our standard testbed (the ASUS A8V Deluxe mainboard), using an ordinary air cooler from AVC described earlier. For a higher efficiency of overclocking, I increased the CPU voltage by 10%: from 1.5v to 1.65v.
The Athlon 64 4000+ comes first. This processor works at a frequency of 2.4GHz, and its maximum multiplier is fixed and equals 12x. To overclock this CPU you need to increase the frequency of the clock generator. Having experimented for a while, I found that the maximum frequency of the clock generator the processor was stable at was 220MHz. The frequency of the CPU itself was 10% above the norm in this case, or 2.64GHz.
So, the overclocking potential of the Athlon 64 4000+ is the same as with the Athlon 64 FX-53 we tested before. Using air cooling you can speed these processors up to about 2.6GHz. By the way, this is yet another confirmation to the fact that it’s practically impossible to produce 130nm CPUs clocked at frequencies of over 2.4GHz in mass quantities.
Next goes the more interesting sample, the Athlon 64 FX-55, which is manufactured using special tricks like spot application of strained silicon. Thanks to that, its overclockability should be higher than that of the Athlon 64 4000+. Moreover, the Athlon 64 FX-55 is intended for non-compromise enthusiasts and its multiplier is not locked, so you can overclock it by simply increasing the multiplier in the BIOS Setup.