The iPhone processor speed has evolved since the first iPhone generation. Underclocking though, is notable among iPhone processors. They ran at a speed lower than what they are specified to operate at – major reason is to maximize the battery life of the smartphone.

The first three iPhone generations use Samsung processors, until Apple decided to design their own processor in the iPhone 4, the Apple A4 processor. Samsung is also the manufacturer.

(jump to the iPhone processor comparison table)

iPhone 1 (original) Processor

The first generation iPhone, or iPhone Original, uses a Samsung 32-bit RISC ARM processor. It has a specified speed of 620 MHz, but clocked almost one third lower i.e. 412 MHz.

iPhone 3G Processor

Same to its predecessor, the iPhone 3G uses the same 32-bit Samsung RISC ARM processor. Specified clock speed and underclocking rate are alike as well. 600 MHz underclocked at 412 MHz.

iPhone 3GS Processor

The iPhone 3GS processor is another Samsung manufactured chip. One of the major improvements though, besides the speed, is the use of ARM Cortex-A8 instruction set, which is able to achieve twice instructions per clock cycle. From a specified speed of 833 MHz, this iPhone 3GS processor is set to run only (underclocked) at 600 MHz

iPhone 4G Processor

The latest iPhone generation is equipped with an Apple A4 processor with ARM Cortex-A8 technology. The speed is rated at 1GHz, and is underclocked at 800 MHz. This CPU is also used on the iPad 1 processor. However, it runs at its full 1GHz speed in the Apple tablet.

iPhone Processor

· Comparison chart

iPhone 1 iPhone 3G iPhone 3GS IPhone 4
Type ARM 1176JZ(F)-S ARM 1176JZ(F)-S ARM Cortex-A8 Apple A4
Spec Speed 620 MHz 620 MHz 833 MHz 1 GHz
Actual Speed(underclocked Speed) 412 MHz 412 MHz 600 MHz 800 MHz