Could my mother board damage my hardrive

I recently had a problem with my PC (Dell). It would't boot so after I tried every option on the BIOS and nothing would work I unpluged the
wire that goes from the hardrive to the mobo. That time it worked just fine,
but then it happened again and I accidently unpluged the small wire that goes from the power supply to the mobo and plugged it back while it was on After that I started to get a message when I boot saying "diskette drive 0 seek failure" so I figured I had killed my hardrive. After that I installed another functioning hardrive to see if it would boot, but it didn't so I put that
working hardrive back on the other good PC and then I started to get the same error that I was getting on the bad PC "diskette drive 0 seek failure". Can some one tell me if the mother board on the bad PC could be killing the hardrives or if it could be another part of my computer that I would be able to fix. I would appreciate any help. Thank You!