Your question makes no sense in its present state.
The title refers to quad core and i7, so i start with that one. An i7 is a quad core, that is it has 4 physical CPU cores, it also has hyper threading so it has 2 logical cores for each physical one so it performs better than the quad core i5s which only have 4 physical cores and 4 logical cores in multi threaded tasks.
Im going to ignore the part about hard drives in the title line since they are CPUs not hard drives.
As for the body of the message, the i7 has 4 processing cores, not 7.
Now, was there a secret question in there that i missed?