Painfully slow iMac

[dangerfish]

I have a late 2009 27" iMac, Core i7 with 1TB HD and 16GB RAM. The system has suddenly become unusably slow. Programs bounce in the dock forever, Safari won't load, just generally unresponsive. The hard drive has been replaced once a couple of years ago. I don't think there have been any recent software additions.

I've tried:
Verify disc
Repair permissions
Reset PRAM
Reset SMC
Cant run Apple Hardware Test: It just won't start up
Safe Boot: Computer still slow
Activity monitor: nothing that stands out.

Appears to be significantly better when booting off an external HD with a backup but still not as quick as I would expect. But maybe that's normal since its an external drive.

I figure its got to be either the HD or the logic board. I'm hoping its the HD but I was able to verify the disc and repair permissions.

Any thought on what the problem might be?

TIA

 

[Sackvillenb]

Based on your symptoms I'd say it probably is the hard drive, or something related (e.g. hard drive cable). I'd back everything up and take it in to the Genius Bar for sure. Good luck!

 

[iDutchman]

100% sure the HDD is failing. I'd pop in a new HDD and install a second SSD in the optical drive bay while you're in there.

My 2009 i7 iMac flies with 16Gb's, 2TB HD and 120gb SSD (samung 840).

 

[dangerfish]

100% sure the HDD is failing. I'd pop in a new HDD and install a second SSD in the optical drive bay while you're in there.

My 2009 i7 iMac flies with 16Gb's, 2TB HD and 120gb SSD (samung 840).

Ya, I've ordered a new HD and a Samsung 840 256Gb to install (Fusion Drive, here I come!). I got both a Super Duper backup and a Time Machine backup. However the Time Machine hasn't backed up since yesterday. I wonder if it is having trouble backing up since its possibly trying to back up a failing drive.