Remove one of the side covers of the computer and carefully examine the motherboard. It should be written the manufacturer and model. The location of the label differs on different models of motherboards you can look for the inscription over the slot of the graphics card, between the CPU and the memory slots on a white sticker near the processor. The advantages of this method: accuracy and no need to install additional software.
Cons: complexity
You can also view the model of the parent Board when you boot up your computer (in the first or second splash screen when you turn it on.Pros: accuracy and ease.
Cons: not every motherboard supports this feature.
If you have installed Windows operating system, you can use special software (for example, Everest, CPU-Z, Astra32), with which you will get the most accurate information.
If your computer is running Linux, you can install the program Top, which is the Manager of all processes in the computer.The pros of this method: convenience and reliability.
Cons: need to install the program