RE: Can I Change Dell Inspiron 15 7000 Graphic Card ?
You are misunderstanding the expression "Switchable Graphic Card", it doesn't mean that You can replace the graphics card inside a notebook, here is what it means:
The Intel Core i series CPU's have included a small graphics card, called HD xxxx, ie. Intel Core i5-4200U has integrated the HD Graphics 4000, and Intel Core i7-4500U has integrated the HD Graphics 4400.
The HD xxxx integrated graphic cards can't play high end games, but they don't use a lot of power, so they are good for Your battery performance.
A lot of laptops come with a separate graphics card for gaming, which is a lot better than HD xxxx, it is typically integrated on the main board of the laptop, and can't be replaced.
Windows can automatic switch between the HD xxxx, and the separate graphics card, if needed, that's why it's called "Switchable Graphics".
The separate graphics card is only used when needed, in order to make the battery last as long as possible.