The Core i5 is a CPU series manufactured by Intel aimed at mid-range computers. In this tutorial, we will present a series of quick reference tables for you to compare the main differences between all models released so far.

Currently, there are two different generations of this CPU around, using a completely different internal microarchitecture. The 4xx, 5xx, 6xx, and 7xx models are based on the “Nehalem” microarchitecture and are also known as “first generation,” while the 23xx, 24xx and 25xx models are based on the “Sandy Bridge” microarchitecture, and are known as “second generation.”

In the past, Intel processors used an external memory controller located in the north bridge chip (also known as Memory Controller Hub, MCH). This means that with CPUs using this older architecture, the chipset (and therefore, the motherboard) is the component that sets the type and amount of memory you can install in the computer. With the Core i processor line, the memory controller is embedded in the CPU, and it is the processor (and not the chipset) that sets the memory type and amount you may have installed in your system. The motherboard, however, may have a limitation on the amount of memory you can install.

The memory controller integrated in the Core i5 accepts only DDR3 memories, supporting the now standard dual-channel architecture up to 1.6 V. Memory modules which require voltages higher than this will not work and may even damage the processor. The speeds supported will depend on the CPU model, as we will present in the next pages.

Core i5 CPUs also have an embedded PCI Express 2.0 controller, so with these processors, the video card is connected directly to the CPU, which in theory can improve the practical bandwidth achieved. These CPUs can access one video card at x16 transfer rate or two at x8 speed each. Because in these models the PCI Express 2.0 controller is integrated inside the CPU, Intel decided to use a lower-speed bus called DMI (Digital Media Interface), which operates at 1 GB/s (first-generation Core i5) or 2 GB/s (second-generation Core i5) in each direction, to connect the CPU to the chipset. This bus was used to connect the north bridge chip to the south bridge chip on previous chipsets from Intel. The lower bandwidth isn’t a problem, since a high-bandwidth bus is no longer needed given that the video card and memory are now connected directly to the CPU.

All Core i5 models are manufactured using 32-nm technology and have an integrated video controller. The on-board video is controlled by the CPU and not by the motherboard chipset, with the exception of three first-generation models (7xx models), which are manufactured using 45-nm technology and don’t have an integrated video controller.

Core i5 CPUs have a base clock from which all other clocks are derived. The default base clock is 133 MHz for all first-generation models and 100 MHz for all second-generation models.

Core i5 processors have Turbo Boost technology, which is an automatic overclocking feature (i.e., the CPU increases its clock rate above the official number when it “feels” that the system is requiring more processing power).

The main technical features of Core i5 processors include:

• Nehalem (4xx, 5xx, 6xx and 7xx) or Sandy Bridge (23xx, 24xx or 25xx models) microarchitecture 
• 64 KB L1 cache (32 KB data + 32 KB instruction) per core
• 256 KB L2 cache per core (renamed to “mid-level cache” or “MLC” in the Sandy Bridge microarchitecture)
• 3 MB (for all mobile models), 4 MB (6xx desktop models), 6 MB (23xx, 24xx and 25xx desktop models), and 8 MB (7xx desktop models) shared L3 cache memory (renamed to “last-level cache” or “LLC” in the Sandy Bridge microarchitecture)
• Dual-core or quad-core technology
• Socket 1156 on Nehalem-based desktop models, socket 1155 on Sandy Bridge-based desktop models, socket 988 or 1288 on Nehalem-based mobile models, socket 988 or 1023 on Sandy Bridge-based mobile models
• DMI bus (1 GB/s per direction on Nehalem-based models or 2 GB/s per direction on Sandy Bridge-based models) 
• Integrated memory controller supporting DDR3 memories in dual-channel architecture (see next pages for supported speeds)
• Integrated PCI Express 2.0 controller (one x16 lane or two x8 lanes)
• Integrated DirectX 10 (Nehalem-based models) or DirectX 10.1 (Sandy Bridge-based models) video processor, except 7xx models
• Intel Turbo Boost Technology 
• Virtualization technology 
• Intel EM64T technology 
• Hyper-Threading (HT) technology on dual-core models
• SSE4.2 instruction set
• AES-NIS instruction set
• AVX (Advanced Vector Extensions) instruction set (Sandy Bridge models only) 
• Execute Disable Technology 
• Enhanced SpeedStep Technology
• 45-nm (7xx models) or 32-nm (all other models) manufacturing process

For a more detailed explanation about the Core i5 processors with all the differences between the Nehalem microarchitecture and the Sandy Bridge microarchitecture, please read our “Inside the Intel Nehalem Microarchitecture” and “Inside the Intel Sandy Bridge Microarchitecture” tutorials. 

Let’s now take a look at all Core i5 models launched so far.