ARM IEM technology is a combination of hardware and software designed to reduce power and energy consumption on the CPU by up to 60%. In an overall system, such as mobile phone this can equate to 15-20% system saving.
ARM IEM technology implements advanced algorithms to optimally balance processor workload and energy consumption, whilst maximizing system responsiveness to meet end-user performance expectations. For the end-user there should be no perceived reduction in their experience, whilst at the same time battery life will be increased. IEM works with the operating system and applications running on the mobile phone to dynamically adjust the required CPU performance level through a standard programmer's model. The IEM technology uses a technique called Dynamic Voltage and Frequency Scaling (DFVS) to implement the power and energy savings. The IEM technology consists of the IEM software, the Intelligent Energy Controller (IEC), and the Advanced Power Controller (APC), which uses the PowerWise™ technology. If the above video doesn't play, try downloading the file here. The demonstration above uses a Linux open source 3G graphics video called Red’s Nightmare. The video is the capture of IEM software running on a DFVS capable hardware platform. The black line represents IEM’s performance prediction, from 0 % to 100% of maximum CPU performance. The red line represents the next nearest supported hardware performance level, of which there are four in total. Even during this video clip it is obvious that the 3D graphics video does not require the full performance of the processor for the whole video. There are times where there is less activity on the screen, it is at these points that IEM looks to reduce the CPU performance to save power and energy. The IEM software varies its performance prediction based upon the workload of the processor. If the IEM software sees performance can be reduced for a period of time, it will instruct the CPU to reduce its performance to match (reducing voltage and frequency). | 
