Processor performance is not the only characteristic that we have been paying special attention to lately. Another important parameter is, of course, power consumption and heat dissipation. The reason for that increased interest is certainly not the electrical bills that may certainly be a serious argument in favor of this or that solutions.
The thing also is that computer systems have become so conventional these days that there appeared the whole bunch of consumer devices based on x86 processors. Take, for example, HTPC – small form-factor systems that perform the functions of a home media center. CPUs consuming a lot of power and hence dissipating a lot of heat cannot suit for systems like that, because there is simply no way to ensure their proper cooling.
Moreover, a lot of users try to make their systems as quiet as possible. This parameter is directly connected with the power consumption and heat dissipation characteristics: more economical processors can often do with passive cooling or cooler using quiet slow rotating fans.
Therefore, we performed a separate test session to measure the power consumption of the systems (without the monitor) built on our tested processors. The platforms configurations were the same as in the performance tests we have just discussed. Enhanced Intel SpeedStep and Cool’n’Quiet power-saving technologies were enabled. We used Prime95 25.5 utility to load the CPUs to their maximum.
In idle mode the systems built with different CPUs do not differ much in terms of their power consumption. It is actually not surprising, because the above mentioned power-saving technologies affect the power consumption of all processors, so in idle mode it is other hardware components that make the biggest contribution into the final result. At the same time, I would like to say that Intel processors are overall a little better here.
In burn mode the situation changes dramatically. The differences in processors power consumption rates are noticeable with the naked eye.
Top AMD processors based on 90nm core suffer a complete fiasco here. Frankly speaking, this is exactly what we have expected, because they feature the highest nominal TDP of 125W. Athlon 64 X2 processors on the newer 65nm Brisbane core prove much more economical, although they still cannot outperform Intel solutions. Only the slowest Athlon 64 X2 CPUs can boast the same power consumption as the top Intel Core 2 Duo E4000 processors also using 65nm core. As for the newest dual-core Wolfdale CPUs, they consume even less power, which most likely makes them the most optimal choice from the performance-per-watt standpoint. The today’s most economical dual-core processors are the new Celeron E1200 and Pentium E2000 series. These processors work at lower clock frequencies and have small L2 cache.