Closer Look at AMD Athlon II X2 250u
If we were to rank AMD processors according to their heat dissipation, we’d be able to single out six classes. The majority of desktop processors from AMD have a TDP of 95, 80 or 65 watts, depending on the number of cores. Some enthusiast-targeted models may even get as high as 125 and 140 watts. As opposed to that, the energy-efficient models have a heat dissipation of 45 or 25 watts. The dual-core Athlon II X2 250u belongs to the latter category as its TDP is 25 watts. The letter “u” in the model name obviously comes from “ultra energy efficient”. AMD’s ordinary energy-efficient processors with a TDP of 45 watts are marked with the letter “e”.
The 25 W dual-core Athlon II series currently includes only two models. Besides the Athlon II X2 250u, there is a faster modification - Athlon II X2 260u. Both are produced in exactly the same way, however. These ultra-economical CPUs are simply downclocked (the opposite of overclocked). As you know from our article called CPU Overclocking vs. POwer Consumption, it is the CPU voltage that affects the heat dissipation and power consumption of an overclocked processor the most. Increasing it leads to a considerable increase in the CPU thermal and electrical parameters. The opposite is true, too: if you reduce the voltage, you will make the CPU consume less power and dissipate less heat. Therefore, it is no wonder that AMD’s energy-efficient processors have a reduced voltage. For example, the ordinary Athlon II X2 with a TDP of 65 watts has a default voltage up to 1.425 volts whereas its 25 W cousin has a default voltage of 1.15 volts or less.
The downside of the reduced voltage is that such a CPU has to be clocked at a lower frequency and proves to be considerably slower than its full-voltage counterparts. For example, the Athlon II X2 250u has a clock rate of only 1.6 GHz, which is much lower than the clock rate of the ordinary Athlon II 250.
On the other hand, the Athlon II X2 250u remains a full-featured member of the Regor family. It is based on a 45 nm die, has two computational cores (each with a dedicated 1 MB L2 cache), and is compatible with the Socket AM2/AM3 infrastructure, supporting both DDR2 and DDR3 SDRAM.
Of course, there is no use in comparing the performance of an energy-efficient processor with an ordinary one that has a clock rate higher than 3 GHz. The result is obvious beforehand. The difference in power consumption is obvious, too. Working at a clock rate of 1.6 GHz with a voltage of 1.06 V, our CPU had very low power consumption – no higher than 18 watts – under full load.
The results of a temperature test were downright funny. Using a Scythe Shuriken cooler, we tried to fry our Athlon II X2 250u up with the LinX 0.6.3 utility but the CPU did not get any hotter than 30 °C.
Even more amazingly, this CPU could run LinX for an hour after we had removed the fan from the Scythe Shuriken cooler. The max temperature was 66 °C with passive cooling like that (on an open testbed).
So, AMD has managed to produce a very economical processor that is eligible for a job in any energy-efficient and compact system. And if the system case is properly ventilated, this CPU can even work with a passive cooler!