let's say I have a 1TB drive divided into 2 partitions, one partition has OS and apps and the second has media on it.


If the media partition is fragmented will it also slow down the OS partition?

 

Yes, because the os has to look through the drive to find files.

 

It will not slow down OS operations. It will slow down multitasking when reading media files.

 

It shouldn't slow down anything when you're not accessing the multimedia partition. If I was you and the multimedia partition is severely fragmented I would still defrag it.

 

As has been said before, it will not affect performance unless you are trying to access the media files. Then and only then.

However you may still feel some slight performance loss, because once a partition is mounted it is actively being used. It shouldn't really be measurable, though. Also, windows will index the files for searching purposes, which can also cause performance loss. (This is an option in the drive properties)

Also, if I were you or anyone else for that matter, I would suggest getting Diskeeper. It will automatically defrag your hard drives by recognizing when you are writing/deleting from the harddrive and automatically optimize it.