Installed a third hard drive and computer is now very slow

[Minute]

Alright so I have:

OS: Windows 7
CPU: i5 2500k
RAM: 2x4GB Mushkin
MOBO: Asus P8Z68 V-pro
PSU: XFX 750W
GPU: 2x HD 6950

HD#1: OCZ Vertex 3 120GB SSD
HD#2: 500GB Seagate Barracuda
HD#3: 1TB Seagate Barracuda

Ok, so the formatting and installation(initiation? not sure of the correct word here) of the third drive was fine. Computer ran fine, I could move files in and out of the drive. Shut off comp, and start it up today and I get an incredibly slow start up. At first I thought it failed to boot, so I left it on instead of turning it off and it actually started up. Gets to the desktop fine, but starts up everything incredibly slow. Normally from when i push the power button and to when I can start firefox it takes me less than 50 seconds, but this took maybe 20+ minutes. I google up possible causes, find a ton of varying answers (at this point i didn't consider the 1tb HDD to be the problem). Realized that it could've been the 1TB HDD, so I open up My Computer to see if I can access it, and sure enough when i tried to explorer.exe crashes. So i shut down the comp, unplug the power and SATA cable from the third drive, start up the computer and it starts up fine.

But I'm completely confused as to what the problem is, is the hard drive bad? If it is why did it run fine the first time around and why is it only showing problems now? I'm going to try and troubleshoot more tomorrow, but if you have any ideas on what i should check for please let me know.

 

[sonexpc]

Check your Hard Drive use crystal disk info first .. it show the internal SMART value
http://www.sonexpc.com/support/how/1/0

Also looking in your Window 7 Event Viewer to see any log for the error

 

[Minute]

Check your Hard Drive use crystal disk info first .. it show the internal SMART value
http://www.sonexpc.com/support/how/1/0

Also looking in your Window 7 Event Viewer to see any log for the error

Ok, sorry it took so long to get back to you. But when I run that Crystal Disk thing, it shows "Unknown" for the third Hard drive.

http://imgur.com/a/SwnVX#QkPZZ

Also my computer when I click on it (Local Disk (E: )) explorer.exe crashes.

EDIT: I was able to get the smart values from Seatools, and it said all the drives passed
EDI2: I was able to format the drive, once that was done the computer started running a little faster again. But Crystal Disk is showing an error of C5 and C6 while Sea Tools is showing no errors.
EDIT3: Ok, so it seems after running multiple test the results seem to switch back and forth. I'm not sure what to make of it, but sometimes Sea Tools will fail a test and sometimes pass it. I've begun the RMA process with Seagate, hopefully this will help anyone else out with the same problem.

 

[Minute]

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