Closer Look at 3rd Generation Intel Core i5
Back one and a half years ago, when Intel launched second generation Core processors, they introduced clear classification of processor families, which they have maintained since then. According to this classification, the fundamental features of the Core i5 are quad-core design without “virtual multi-threading” technology – Hyper-Threading and 6 MB L3 cache. These peculiarities were typical of the previous generation Sandy Bridge processors and were carried on in the new Ivy Bridge CPUs.
It means that all Core i5 processors with the new microarchitecture are very similar. To some extent this allows Intel to unify the production: all today’s Ivy Bridge Core i5 processors use identical 22 nm semiconductor die with E1 stepping that consists of 1.4 billion transistors and is about 160 mm2 big.
Despite the similarities all LGA 1155 Core i5 processors share in formal specifications, the differences between them are obvious. New 22 nm manufacturing process and Tri-gate transistors allowed Intel to lower the TDP of the new Core i5 processors. The LGA 1155 Core i5 CPUs used to have 95 W TDP, but the TDP of the new Ivy Bridge processors has been lowered to 77 W. However, despite the lowering of the TDP, the clock frequencies of the Ivy Bridge CPUs haven’t been increased. Just like their predecessors, the top previous generation Core i5 processors work at 3.4 GHz maximum clock frequencies. It means that the performance advantage of the new Core i5 processors over the old ones results only from the microarchitectural improvements of the computational resources, which has also been confirmed by Intel developers.
Speaking of the strengths of the new processor design, we first of all would like to stress the modifications applied to the graphics core. Third generation Core i5 processors use a new modification of the Intel’s graphics accelerator – HD Graphics 2500/4000. It supports DirectX 11, OpenGL 4.0 and OpenCL 1.1 software interfaces and in some cases may offer better 3D performance and faster HD video transcoding into H.264 format using Quick Sync technology.
Moreover, Ivy Bridge processor design also has improved “uncore” - memory and PCI Express bus controllers. As a result, systems with the new third generation Core i5 processors can fully support PCI Express 3.0 graphics cards and can clock DDR3 memory at higher frequencies than their predecessors.
The third generation desktop Core i5 processor family (that is Core i5-3000) has barely changed since its official public debut. Only a couple of intermediate models have been added to the lineup, which adds up to a total of five models (if we do not take into consideration energy-efficient models with restricted TDP). If we add here a few Core i7 CPUs on Ivy Bridge microarchitecture, we will get the entire lineup of 22 nm processors for LGA 1155 form-factor:
The table above, obviously, requires some comments regarding the functioning of the Turbo Boost technology that allows processors to increase their clock frequency as the power and thermal conditions permit. In Ivy Bridge this technology has been slightly modified, and the new Core i5 processors can overclock a little more aggressively than their predecessors from the Sandy Bridge family. With minimal improvements in the microarchitecture of the computational cores and no clock frequencies increase this is exactly the feature that can guarantee certain advantage over the predecessors.
The maximum frequency that Core i5 processors can reach with only one or two cores fully utilized is 400 MHz higher than the nominal. If the load is multi-threaded, then Ivy Bridge Core i5 processors may raise their clock speed by 200 MHz above the nominal provided the thermal conditions are favorable. In this case Turbo Boost efficiency will be the same for all above mentioned processors, and the only difference from the previous generation CPUs will be higher frequency increase when utilizing two, three or four cores: Core i5 from the Sandy Bridge generation head 100 MHz less headroom for frequency growth in this case.
Using the diagnostic CPU-Z utility let’s take a closer look at all the members of the Core i5 Ivy Bridge processor family.