My iMac goes to sleep and won't wake

[DavoDavo]

Hi All,
My iMac (20" core2 duo 5,1) running a fresh install of Snow Leopard 10.6.8 from an external USB disk does not wake from sleep and I have to reboot.
I got this error last time:

15/01/13 12:57:31 PM configd[13] Wake: Drivers Failure panic - AC - PEGP HDEF RP01 USB1 USB2 USB3 USB4 USB7 PATA
com.apple.message.domain: com.apple.powermanagement.wake
com.apple.message.signature: Drivers Failure panic
com.apple.message.result: Failure

I intend to put this external HDD into my iMac as the boot drive but don't want to do that if there is a problem with the iMac itself. I previously replaced the original 250GB HDD because it was running out of space but the one I put in (a used 500GB SATAII) seemed to have a problem as it went to sleep when it felt like it and I had to wait before it decided to wake up, but after it did wake everything behaved normally for a while.
The external HDD I am booting from is the same age and make/model as the current internal HDD (the one that goes to sleep intermittently) both HDD's came out of a failed LaCie 2Big NAS, but they checked out OK before I installed Snow Leopard on them.

So, does my Mac have a problem that is now showing worse because my boot drive is now on the USB?

Thanks,
Dave.

 

[DavoDavo]

Some more info...

After I installed the replacement 500GB drive (with a fresh OS install), the Mac would hang while I was using it - i.e., during normal use, and then eventually resume - and then do it again later, and again, and again, etc...
With the USB connected same make/model drive I don't have that problem, it's only if I leave the Mac powered up and walk away for an extended period - it refuses to wake up.

Hoping someone can throw some light on this problem, I don't want to pull my Mac apart again to put the second HDD in it only to find I have the same problem as before.

Update, I just replaced the iMac internal HDD with the one that was in the external USB case, shall see how it goes with nothing plugged in except LAN and keyboard/mouse. Keeping my fingers crossed! Oh, I just remembered, I have my Cinema display plugged in too - but not its USB and Firewire plugs.

 

[DavoDavo]

Faulty HDD's?

Well,
I persevered with the second HDD but got fed up with the iMac still hanging for no apparent reason whenever it felt like it.
Decided to buy a new HDD and put that in, then I discovered that I could buy an OWC SATAII 480GB SSD for a reasonable price and bought one.
I put it in an external USB case and loaded up Snow Leopard. Booted from that and it worked fine - no hangs or funnies. Ran that for a while with no problems.
So I took a deep breath and opened up the iMac again and put the SSD in it. So far (early days yet) it is working fine and, of course, there is a definite improvement in boot times and general app launching etc, as to be expected. It certainly has given my iMac a new lease of life.

Unfortunately, when I put the iMac back together I forgot to plug the HDD heat sensor in so when I fired up the Mac the HDD fan went berserk! So I had to open up the iMac again (fourth time; I'm getting quite expert at it now).

So, at the moment it looks like both the 500GB HDD's I put in have the same fault, why they played up I don't know as they appear to check out OK.

 

[DavoDavo]

Yep, those HDD's seem to have a strange problem!

Update.
Been using the iMac daily for extended periods since installing the SSD (and reconnecting the fan sensor). All is working as it should, no more hangs.

So it looks like both (same model and vintage) 500GB Samsung HDD's have some sort of problem when installed in my iMac.
Pretty weird huh?

Both HDD's and the SSD are SATAII.
I did wonder whether SATAII drives might have been incompatible with my iMac (SATAI) but I was assured by OWC that the SSD was compatible and that has proved to be the case.

Saved me buying a new Mac, the SSD has made quite a difference in boot times, and with opening apps and shutting down.