WD Black 750 Often Slow and Unresponsive

I own a M/N: WD750WAAEX-00Y9A0 750gb Black Drive.  I’ve been experiencing weird freeze ups that are caused by this drive.  I have Windows 8 installed, and the Task Manager shows the hard drive peg at 100% “Active Time” and the performance monitor also pegs disk que length at 100 as well.  

Last night I decided to try and backup some of my data.  Transfer rates over gb network to a NAS was bouncing between 50 kb - 1.5 mb /s transfer.   It took almost 2 hours to backup 4gb of data.

After that, I powered down the system to try the 6gb sata 3 port as I was plugged into a regular sata 2 controller.  Powered the system back on and all seems much better.   

Fast forward to this morning, it seems to have random freezes again but not as extreme as before.   I just did a 2gb transfer to my storage space and got a transfer rate of 110mb/s constant which is very good imo.  

Does anyone have any advice for things I should try?   I was considering replacing sata cables…   Recently (this week) I changed cases and have now added 2 more hard drives to my computer which have been added to my Win8 storage space.  But during the case switch, I chose the nicest/newest cables for the main hard drive.  The sata cables do run extremely close a many power cables, can interferance cause problems?  Didn’t think there would be considering its all DC power. 

Have you tried testing the unit with DLG tool?

Might be getting corrupted… if so, remove the information from the drive and write zeros to it.