Intel DH55TC Motherboard - Core i5 661 CPU Review :: Intel Core i5-661 CPU

• Graphics Media Accelerator HD (GMA HD)
• Native Dual Core
• Hyper-Threading
• Smart Cache
• Integrated Memory Controller IMC 2 ch DDR3 up to 1333MHz
• Advanced Encryption Standard-New Instructions
• Halogen-free
• Turbo Boost technology
• 4MB L3 Shared cache
• 900MHz core frequency
• Intel Virtualization Technology
• AES New Instructions
• 2 Dual channel DDR3 Memory channels
• Hyper-Threading
• Intel H55 Express chipset support
• 32KB L1 instruction and 32KB L1 data cache per core
• 256KB L2 cache per core
• 45nm manufacturing process
• 731 million transistors
• Direct Memory Interface

Intel's Core i5-661 CPU is part of the mainstream version of Intel's Nehalem architecture called Clarksdale with two cores on the same die as the integrated graphics. Clarksdale is a 32nm processor with two cores. The Core i5-661 adds Intel's GMA HD integrated graphics to the processor and Intel's Identity Protection technology. The new processor also features support for Intel's Advanced Encryption Standard Instructions Set. Here is a table with the new CPUs:

You'll notice that the various CPUs are within 266MHz of each other in clock speed for the Core i5s. The highest clocked Core i5 in the lineup will be the Core i5-670 running at 3.46GHz with a maximum Turbo Speed mode of 3.73GHz. The Core i5-661 I'm reviewing today has a rated clock speed of 3.33GHz with a Maximum Turbo Speed mode of 3.6GHz. The maximum memory speed supported by the CPU's Internal Memory Controller is 1333MHz without overclocking. The TDP is 87W and the Core i5-661 is expected to retail at $196.

Turbo Boost is Intel's technology to speed up the CPU. In the LGA-1366 CPUs like the Core i7 920, the Turbo Boost feature was only able to speed up two stepping at the most. With the advent of the LGA-1156 CPUs like the Core i7 860 and Core i5 750 the steppings available to the CPU when one core is used are substantial. The Core i5 661 has a modest increase in speed with Turbo Boost to 3.6GHz from the 3.33GHz default clock speed.

The Core i5-661 has 32KB of L1 instruction and 32KB L1 data cache per core, meaning it contains 128KB of L1 cache total. The CPU also has 256KB of L2 cache per core and a unified 4MB L3 Smart Cache. This is compared to the 8MB found on the Core i7 CPUs. Intel has implemented Hyper-Threading in this CPU meaning that it can work on two threads at the same time instead of one, showing four logical processor cores in the OS.

Intel's Graphics Media Accelerator High Definition is basically the same chip used on their GMA X4500HD integrated graphics with a couple of exceptions, including the number of execution units and OpenGL support.. Previously, Intel put the integrated graphics into the Southbridge, separate from the CPU. With the advent of the Clarksdale CPUs Intel has integrated the graphics chip onto the CPU itself, meaning a better package for the system builder.

Intel has increased the execution units on the GMA HD from 10 to 12 on the chip. The second change is the increase in clock speed that differs on each of the CPUs in Intel's lineup. The IGP on the Core i5-661 has a clock speed of 900MHz. This is a huge increase over the clock speed of the GMA 4500 HD which is the latest version of the integrated before this one. The GMA HD has support for DirectX 10.0 including Shader Model 4.0 and OpenGL 2.1. This added support for the OpenGL Shading Language 1.20, Pixel buffer objects and SRGB texture formats to OpenGL.