What about the fans for the graphic card?
What about them? All graphics card will come with at least a heatsink, most newer cards with a heatsink+fan, that doesn't have anything to do with the cooling on your CPU. The graphics cooling solution is already on the card when you buy it, if you change the card, all of it changes, if you don't get a new card, you don't have to change anything else.
A CPU heatsink is different and doesn't come attached, because the computer doesn't come all in one, like a graphics card does. Think of it like this:
Your computer has 3 main components, motherboard, CPU and memory. Of course there are others which are vital, hard drive, power supply etc, but for the sake of this, it has only those 3. They are all separate. You have to get the motherboard, put the memory into the DIMM slots, put the CPU into the CPU socket, then put the heatsink one. There are many different types of memory you can use, many different types of processors, and many different types of processors, so they can't make it all one, the sure must choose what they want, and put it all together, and you can't just magically push the CPU through the heatsink, you have to put the CPU in the motherboard socket, then the heatsink on top
A graphics card however, is 1 single full circuit board. It has the PCB, GPU and VRAM all on the same board, all soldered on, none of it can be modified, there is 1 type of memory, 1 GPU and 1 PCB, there are no variations like there are with the core of your computer. There is never a reason to take it apart, other than to take the heatsink off for cleaning/reapplying thermal paste/replacing. Everything is all there and ready, because every single one of those video cards is identical, so they are able to put the cooling solution on there.