Intel Core i5-520M vs Intel Core i7-2657M

Intel Core i5-520M

The Intel Core i5-520M is a dual core CPU for laptops and clocks (due to the Turbo Mode) from 2.4 to 2.93 GHz. Each core is based on the Nehalem (Westmere) micro-architecture. Hyperthreading enables the Dual Core CPU to handle 4 threads at once (for a better usage of the pipeline). Compared to the faster Core i7-620M, the 520M features only 3 MB Level 3 Cache and a lower clock speed (CPU and GPU).

A feature of the new Core i5-520M is the integrated graphics card called GMA HD and memory controller. Both are on a separate die that is still manufactured in 45nm whereas the CPU die is already manufactured in the new 32nm process.

The performance of the i5 520M is on average faster than a Core 2 Duo T9500 and due to the Turbo Boost, single threaded applications run even better. Therefore, the Core i5-520M is as fast as high clocked Core 2 Duo CPUs and should handle most gaming and multimedia tasks well.

The 32nm cpu cores of the Westmere generation can also process some new instructions to accelerate AES encryptions.

The integrated Intel Graphics Media Accelerator HD (GMA HD) graphics card is known to be clocked up to 500-766 MHz and should be clearly faster than the old GMA 4500MHD. A GeForce 9400M (ION) should still be a faster (especially as Nvidia and ATI cards have a better driver support than Intel up to now). According to rumors, the GMA core will also use the Turbo Mode regulate the clock speed.

The power consumption of 35 Watt TDP (max.) counts for the whole package and therefore it is clearly better than the 35 Watt TDP of the Core 2 Duo T-series (CPU alone). Due to the Turbo Boost, the Core i5 more likely uses the TDP under load than the older Core 2 Duo CPUs. Without any load, the i5 uses noticable less power.

Intel Core i7-2657M

The Intel Core i7-2657M is power efficient ULV (Ultra Low Voltage) processor for thin and light laptops. The base frequency of 1.6 GHz is relatively low, but due to Turbo Boost 2.0, the CPU may clock up to 2.7 GHz (on core loaded, 2.4 GHz with both cores loaded). However, this depends on the cooling and power consumption of the laptop. Due to HyperThreading, the i7-2657M is able to handle 4 threads in parallel. Compared to the slower i7-2617M, the 2657M offers a higher clock speed (processor core and turbo, graphics turbo).

Sandy Bridge is the evolutionary successor of the Arrandale architecture. The most noteable improvements is the improved Turbo 2.0 and the integration of the graphics card into the 32nm CPU core. 

The integrated Intel HD Graphics 3000 clocked at 350 or 1000MHz (Turbo Boost). Due to the slower clock rate, compared to HD Graphics 3000 in 35W and 45W processors (usually clocked at 650-1100/1300MHz in non LV processors), the performance should be noticeable lower.

The performance of the CPU should be a bit higher than a similar clocked Arrandale Core i5. In our benchmarks (see below), the ULV processor was as fast as a Core i3-2310M due to the high Turbo Boost frequencies. However, the laptop cooling system has to keep the processor relatively cool for the Turbo Boost to work often.

The TDP of 17W (includes the integrated GPU and memory controller) allows the use of the 2657M CPU in small subnotebooks.