diagnosing whats wrong with my iMac.

I am stumped. I have a 2.8ghz 24'' iMac with 4 gigs of ram running snow leopard i bought last year. It has been a great machine. However recently when I run it hard or let it sit idle for several hours it starts to run slower, and slower, eventually leading to a sbod (spinning ball of death) Then when you reboot it wont find the hard drive. However if you turn it off and let it sit for a bit, when you boot it then finds the hard drive and boots right up. S.M.A.R.T. status shows verified. I took it to the apple store the other day where we figured it was overheating hard drive. (iStat pro showed the hd running at 53c) They replaced the hard drive heat sensor, and the hard drive blower. I was then crushed just a few hours ago when I got it home and tested to see if it had been fixed. It had not. =o(

So now im stumped. What do you think it could be? Any help is appreciated.

Brice

EDIT: Well after digging thew some of these threads I have found a program called smart utility. I believe this program has told me what is wrong, as it says i have 10 bad sectors.Now I am wondering why disk utility would show verified if smart utility is telling me to backup the drive and replace?

Thanks again,
Brice

Sounds to me like the drive is experiencing a slow death.

Disk Utility is not the best at diagnostics. Although, 10 bad sectors is nothing. A manufacturer wouldn't even consider replacing a drive for that. The number of sectors on a drive will vary based on a number of things including file system used, size of the drive, etc. But to give you an idea, a 320GB drive with 512 bytes per sector would have approximately 625,000,000 sectors.

Great little tool SMART Utility and believe me if it tells the drive is failing, time to backup quick to an external and invest in a new drive. DiskWarrior MAY help, but at US$99 dearer than a new HD.

For starters boot from your install DVD, go to Utilities and run Repair Disc and see what is reported. Keep us posted?

Agreed with Harry. Should have been clearer above. While the number of bad sectors wouldn't be the reason it's indicating a failing drive, there is something not right going on with that drive.

Once a drive starts showing bad sectors, it's time to get rid of it ASAP. There are utilities that will allocate out bad sectors, but in my experience, it's only going to get worse until it fails entirely.

And of course, if you haven't already done so, BACK UP!

Took it back to Apple today. They are going to swap the drive, =o) and then do some stress testing. The part that is not setting well with them (or me) is that it seams to be heat related. They did say that it could be the logic board and that it may need to be replaced as well.

Again thanks for your help
Brice

PS Dont worry I backed up. Time Machine is my friend, and i found a cool program (winclone) to backup my bootcamp partition.

EDIT: Hopefully this is the final fallow-up. I just got my iMac back! They did replace the hard drive, but the issue continued so they swapped out the logic board. That seamed to fix the issue. Thanks for reading, and your help.

Brice