IPhone 3GS Clock Speed
- The iPhone 3GS has a module containing the ARM Cortex and the PowerVR SGX, a custom graphics processor. The Cortex runs the 3GS iOS operating system, its applications and utilities; the PowerVR SGX speeds up graphics-dependent programs such as games.
- Every digital electronic device, from the humblest MP3 player to the most powerful computer system, uses an electronic clock. It produces precisely-timed electrical pulses that coordinate and synchronize the device’s various circuits. A clock’s speed governs the device’s speed: generally, the faster the clock, the faster the device. As of 2011, cellphones have clock speeds ranging from 500 MHz to 1 GHz; in personal computers, clock speeds run from about 800 MHz to 3 GHz. The ARM Cortex version on the iPhone 3GS has a clock speed rated at 833 MHz, underclocked to 600 MHz. The PowerVR SGS runs at 200 MHz and draws graphics several times faster than the 3G’s PowerVR MBX-Lite.
- Desktop PCs usually push their microprocessors to their clock speed limits; smartphones, on the other hand, run on batteries and have no fans to cool down a fast microprocessor. Underclocking, or running the ARM Cortex at lower than its rated speed, sacrifices a little performance but both prolongs battery life and lets the 3GS run cooler.
- The earlier iPhone 3G model used an ARM 11 processor rated at 620 MHz and underclocked to 412 MHz. Though the 3GS microprocessor comes from the same maker, ARM, it has a different design from the one in the 3G. This makes it difficult to quantitatively compare performance simply based on their clock speeds. Apple, however, claims a doubling in overall performance for the 3GS over the 3G.
