Why is my pc only detecting 1 ram?

When this happens, it’s usually because the ram sticks are made with different specs.

Specificaly, when you have more than one ram, they should operate on the same frequency. Otherwise your PC choses to detect only one, or none at all. It had occured with my old computer and until i bought identical ram sticks, it would immidiately shutdown after a few seconds,

It would be helpful if the sicks were made by the same manufacturer too, tend to run more smoothly.