RAM (Random Access Memory) is the memory used by the computer to store data from programs in use. Generally, the higher the RAM memory, the more you can run multiple programs at the same time. However, the amount of RAM that you can install on the computer depends on the hard drive and the operating system of the computer. To determine the capacity of RAM memory that you can add to your computer, you will need to know the capacity of your hard drive as well as the version of the operating system you are running.
Steps
Part 1 of 2: check the operating system

Step 1. Determine if you are using 32-bit or 64-bit Windows
The Windows operating system has a maximum capacity of RAM memory. And if the RAM memory installed on your computer exceeds this maximum capacity, the extra memory will not be used. The RAM limit varies depending on whether you are using 32-bit or 64-bit Windows.
- To learn how to determine if your Windows system is 32-bit or 64-bit, read the article How to check if the system is 32-bit or 64-bit. Usually, you can determine if your Windows system is 32-bit or 64-bit by going to System Properties (⊞ Win + Pause)
- 32-bit Windows can support up to 4 Gb of RAM memory.
- 64-bit Windows can support up to 128 Gb of RAM memory.

Step 2. Check your Mac model
The amount of RAM that your Mac can support depends on your Mac model. There are different memory capacities for different Mac computers. Read the documentation for your Mac device to know the exact capacity supported. Some examples of popular Mac models:
- iMac (27 inches, late 2013) - 32 Gb
- iMac (2009, late 2012) - 16 Gb
- iMac (2006-2009) - 4 Gb

Step 3. Determine the memory capacity supported by your Linux system
A 32-bit Linux system will only support 4 Gb of memory, but if the PAE kernel is enabled (which is the case for most Linux distributions) it can support up to 64 Gb of RAM. Theoretically, a 64-bit Linux system can support up to 17 billion Gb of RAM, however, most are limited to 1 Tb (Intel) or 256 Tb (AMD64).
To determine the exact capacity supported by your system, access Terminal by pressing Ctrl + Alt + T. Type sudo dmidecode -t 16. You will be prompted for the administrator password. Find the entry Maximum Capacity
Part 2 of 2: check the motherboard

Step 1. Identify the motherboard
Even though your operating system can support a large capacity of RAM memory, you are still limited by the capacity that your motherboard can support. If you do not have access to your motherboard information, you will need to identify the motherboard and research its specifications online.
You would probably need to open the computer to be able to identify the motherboard model number

Step 2. Read the motherboard documentation
At the beginning of the motherboard documentation, you will find a chart or a specifications page. Find out the maximum RAM or memory capacity of the system that can be installed. You will also see the number of slots available on your motherboard.
RAM should be installed in pairs. If your motherboard supports 16 Gb of RAM and has 4 slopes, you can install 4 strips of 4 Gb each or 2 strips of 8 Gb each to achieve the maximum

Step 3. Use an online program
If you don't want to open your computer or read the motherboard documentation, you can use online programs that can browse your system and determine the capacity of RAM you can install and the type and speed of RAM. supported.
You will find these programs on most memory vendor or manufacturer sites such as Crucial or MrMemory

Step 4. Update your RAM memory
After you have determined how much RAM your system can support, you can install the new RAM. When adding new RAM, make sure the clock frequency matches the original RAM. Read the article How to install RAM memory, for details on how to install new RAM memory.