Closer Look at Sandy Bridge T-Series Processors
Intel has a very simple way of getting energy-efficient processors. At the production process there are no differences between the standard semiconductor Sandy Bridge dies and energy-efficient processor dies with low heat dissipation and power consumption. Only at the very last production stage the CPUs with lower TDP are assigned lower clock frequencies and lower core voltage. These two simple things are more than enough to make second-generation Core processors be assigned to two different groups with dramatically different heat dissipation.
Although the above described approach to creating energy-efficient processors seems to be rather primitive, it works perfectly with Sandy Bridge semiconductor dies and at the same time allows to keep their production cost on the low side. That is why the prices for T-series processors are only a little bit higher than those of regular processor models. So, there are no financial obstacles that could prevent these products from becoming increasingly popular.
Intel currently offers four T-series processors with TDP lowered to 45 W or even 35 W. All of them are from different model line-ups and clock frequency is not their only distinguishing feature. They have different number of computational cores and support different technologies. In other words, they are diverse enough to give the users the opportunity to find the best match for their performance and functionality needs.
Let’s take a closer look at the T-series processors.
Core i5-2500T is the only quad-core processors in the T-series. It was obviously a challenging task to make sure that this CPU fits into the strict energy-efficiency standards. Its TDP is declared to be 45 W, while all other members of the T-series boast 35 W TDP. Therefore, it is not surprising that the nominal clock frequency of this model is only 2.3 GHz, which is an entire gigahertz less than the nominal clock frequency of a regular Core i5-2500.
However, the term “nominal clock frequency” is very relative when applied to Core i5-2500T. This processor supports Turbo Boost technology, which in this case works very aggressively. The table below shows how far Core i5-2500T may overclock when all of its computational cores are evenly utilized. For the same of comparison, we also included the data on Turbo Boost in regular Core i5 processors.
As you can see, Core i5-2500T works at a relatively low frequency only when three or four cores are utilized. When the operational load is not so intense, this processor may be overclocked much better, with the frequency increasing by up to 1 GHz. As a result, this energy-efficient CPU catches up with its fully-functional brothers and with two or three idling cores may even outperform Core i5-2300 or Core i5-2310.
You shouldn’t believe the voltage reading displayed on the CPU-Z screenshot above. In fact, our Core i5-2500T processor received 1.08 V, which is about 0.1 V less than the Vcore of regular quad-core Core i5 processors. So, Core i5-2500T CPU is an energy-efficient processor not only because of its lower frequency, but also because it runs on lower core voltage.
In this respect, the features of the graphics core inside Core i5-2500T pose even greater interest to us. In this case it is Intel HD Graphics 2000 with six execution units, which is integrated into most second-generation Core processors for desktops. However, the frequency of this GPU in Core i5-2500T may vary within a much wider range than by other processors. Its nominal frequency is 650 MHz (vs. regular 850 MHz), but the “graphics Turbo Boost” may increase this frequency to 1.25 GHz (vs. 1.1 GHz in a standard model). In other words, if the GPU and processor cores are not fully utilized all at the same time, then Core i5-2500T will outperform even a 95 W Core i5-2500 processor.