Intel Atom Z3680D vs Intel Core i5-520M

Intel Atom Z3680D

The Intel Atom Z3680D is a power-efficient dual-core SoC for Windows and Android tablets. It is clocked at 1.33 - 2.0 GHz and is part of the Bay Trail-T platform. Thanks to the specially optimized 22nm low-power design process (P1271) with Tri-Gate transistors, performance and energy efficiency have been significantly improved compared to its predecessor. In contrast to the Z3680, the Z3680D offers a different memory controller and a lower display resolution.

Architecture

The processor cores are based on the new Silvermont architecture, which is an out-of-order design for the first time. The increased utilization of the pipeline and many other improvements (optimized branch prediction, increased buffers, and enhanced decoders) have increased the performance per clock by about 50 percent. At the same time, however, the Hyper-Threading feature of the previous generation has been removed. Other major additions are the support for new instruction set extensions such as SSE 4.1 and 4.2 as well as AES-NI (depending on the model).

Performance

Thanks to the improved performance per clock, the Z3680D is faster than previous Intel Atoms like the Z2760. Presumably, the Z3680D even competes with AMD APUs like the AMD A4-4355M. For simple everyday tasks such as Internet or Office the performance is adequate, but not for complex software or modern games.

Graphics

The HD Graphics (Bay Trail) is based on the Intel Gen7 architecture, which supports DirectX 11 and is also found in the Ivy Bridge series (e.g. HD Graphics 4000). With only 4 EUs (Execution Units) and a relatively low clock speed of up to 688 MHz, the GPU is even slower than the HD Graphics (Ivy Bridge). Therefore, only older and less demanding Windows games will run fluently. However, video acceleration and display resolutions up to 1920 x 1200 pixels are no problem for the chip.

Power Consumption

The entire SoC should be rated at an SDP of about 2 W, which would indicate a TDP of less than 4 W. Thus, the chip can be used in passively cooled tablets.

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.