To give you an example of media instructions are.
Pretend the CPU is a person. And the data is like a project that you have to put together.
The person will put the project together faster if he has directions/instructions
But the person will put it together slower but he will still put it together without instuctions. But just my common sense.
Basically a cpu can get a job done by shear power. But if it has semi-specific instructions it can do the job more effiecently.
INTEL i7 930
3x2gb Corsair Dominators
EVGA GTX 480