Very good explanation by Ruthie Franecki above in the answer. If the above steps don’t work and still you are not getting display on your screen, try another method to check your RAM.
Sometimes we don’t know motherboard has also a limited capacity of RAM. Usually, the motherboard came with 4 GB expandable memory using two slots.
Everyone wants higher RAM memory in your system and increase his or her RAM without checking the motherboard is capable or not. Just like you have Intel motherboard and using 4 GB (2-2 GB two RAMs in two slot). Now if you want to increase your RAM you will definitely replace one 2 GB RAM with 4 GB of RAM.
Now you have 6 GB inserted into motherboard and motherboard has the capacity of only 4 GB. In this case, you would not get any display despite your all the RAM are in working condition.
So before upgrading RAM or thinking RAM is faulty make sure you are not using RAM over the capacity of the motherboard.