[Pacabel]

What kind of systems were you working on?

No, you probably don't need to know much about how graphics cards work if you're working with databases or other software that doesn't really involve graphics in any serious way. But if you're working on graphics card drivers, high-end video games, visualization systems, or simulations, then you'd probably should have such knowledge.

The point is not to fully understand every single layer that exists, including those that your software never interacts with, or only just makes very light usage of. But you should have at least a basic understanding all the way down through the code and hardware you do use, directly or indirectly.