What is the difference between the CPU and GPU?

Like a PC now most of the Smartphones specification includes a GPU (Graphics Processing Unit) along with the CPU (Central Processing Unit). Companies like IntelARM and AMD produce the CPU and companies like Nvidia, AMD’s ATI produce the GPU.
CPU and GPU are two very vast and complex topics which cant be explained in one article, my attempt is to give you an overview of the GPU and how it differs from the CPU. So please have the below noted brief overview on both these amazing technologies.


  • What is a CPU?


By the name one can guess what CPU means, it is a central processing unit. It means each event which occur in a system is brought to the CPU for computation. For example a simple MP3 player is a system, it include a small LCD display, buttons, memory, headset, battery and many other internal things which are not visible to the user. Now i am writing this article with the help of a keyboard, so every letter pressed is sent to the CPU for execution. The main execution unit consists of the Arithmetic and Logic Unit (ALU). This unit consists of complex algorithms written by the ALU engineers and these algorithms are executed by the transistors for the final output. CPU needs clock to run, i can relate it to the heart beats. CPU is connected to the other members of the system via bus on a printed circuit board. Most of the CPU manufacturers integrate peripherals like RAM, ROM, input/output ports etc along with CPU in a single chip and such chips are called Microcontrollers. CPU performs Integers calculations like add, sub, mul, div and other logic operations. It cant calculate a floating point, the main reason could be that floating point algorithms are more complex than arithmetic algorithms. So as the complexity increases the power consumption also increases hence dissipating more heat and reducing the life cycle of it.


  • What is a GPU?


GPU is also a processor made up of complex algorithms and millions of transistors but it is designed for a specific purpose, i.e Graphics Processing. Even GPU require clock to operate and it is much faster than the CPU. Because its computation methods are very complex which includes parallel processing, geometry, trigonometry and floating point calculations that re necessary for graphics rendering. It consists of 100′s of cores and it can be seen on a Graphics card or video card which are used in the systems. Main application of a GPU is to render/translate the stored Image/Video onto display unit as quickly as possible. Since GPU works a lot faster than a CPU it dissipate more heat and hence requires a cooling unit. If i play a video in my smartphone, GPU starts storing the video part by part in the frame buffer (like a RAM) in background and triggers these parts one by one to play the video. So GPU does lot of computations before a image or video is displayed. And these computations are performed very fast. The speed is achieved by its complex pipeline architecture and parallel processing ability. Modern GPU use many filter and shaders to display the image more cleaner and crisper.

Best combination of CPU and GPU delivers the best performance and throughput of the system.

Below picture shows the visual realism achieved from modern GPUs like NVIDIA GeForce 8800 GTX.

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