HELP! 2nd HDD removal caused my main HDD to lag?

[Daniel_346]

So ... My brother's Steam decided to uninstall his GTA V So he asked me if i could try to move my Rockstar Social GTA V (the no steam version) into his HDD and i said sure, and heres where it all begins:
- I get his HDD and connect the SATA cable in it and in my pc, aswell as the other wire next to it.
- I turned on my pc just to see the "Verifying dmi pool........." and it wouldnt move on from there.
- I tried only connecting his HDD by putting in the SATA cable and it gave me the error below the verifying dmi pool (cant remember the error - was something to do with no OS or smthn).
- unplugged it totally and returned it to him. after i turned it off and waited 30mins i decided to try again, this time i managed to boot it up.
- transfered the files. shutdown the pc, unplugged the HDD and inserted it in his pc, files were corrupt.
- i tried connecting the HDD again, successfully, however i was getting major lags.. anyhow .. i decided to just transfer the files again and this time they werent corrupt. however after i went to my pc to listen to music or something, it hadnt gotten any less lag-ish from when i last experienced the lag (2nd time connecting the HDD).. Help me please..

What i did to try and fix it so far:
- defrag (it says 1% fragmented).
- the checking tool in: Right click C:\ -> Properties -> tools -> scan (no errors)
- checked my task manager for over abusive of Disk space (everything is normal)
- AVG virus scan (still scanning)
- Booting in safe mode to see if the problem is still occuring. (yet to do so)

PS: please excuse my poor english & I'm not an expert in this field!
please dont ask me if i forgot to off the PC before inserting / removing any wires, im not that stupid, and yes i pulled out the power cord after turning off the pc

 

[Boogieman_WD]

Hey there, Daniel.

You had trouble booting to your own drive while your brother's HDD was connected? This is a bit weird. Anyway, since you've managed to transfer everything you wanted to, the only issue remaining is the lag you are referring to?
Besides the scan you've made it would be best if you could download the HDD manufacturer's diagnostic tool and run all the tests, to see if anything alarming pops up. Make sure that you haven't dislodged any of the cables while you were connecting/disconnecting the other drive, so you could go ahead and test the drive with a different SATA port and cables if possible, to see if the problem still persists.
Of course, if you have valuable data on that HDD, it would be best if you back it up before you do anything else, just to be on the safe side.

Hope that helps.
Boogieman_WD