iMac (24" Early 2008) Hard Drive troubleshooting help

Discussion in 'iMac' started by caaalebbb, Oct 25, 2014.

  1. caaalebbb macrumors member


    Mar 15, 2011

    I recently acquired (for free! :)) an old iMac. My only other computer is a dying 2009 Macbook. I'm a college student that can't afford getting a new computer so this iMac is quite the godsend for me!

    It is an early 2008 24" model with a 2.8 Ghz Core 2 Duo processor, 4GB memory, and the presumably stock WD 320GB 7200RPM hard drive. I've (probably mistakenly) upgraded to OS X Yosemite.

    The machine seems to be in great shape (for its age) it runs nicely for short periods of time, but after awhile – generally after exhaustive HD usage – it gets very slow at particular tasks, and it seems as if the hard drive is the culprit.

    For example, the other afternoon I tried splitting a large, 10GB mkv using Mkvtoolnix; it said it would take 6 minutes, but it kept getting slower and predicting a longer time as the task went on, 12 minutes, 30 minutes, 40 minutes, etc.... I stopped it and retried it and the same thing happened. I gave up but I tried the very same task the next day and it finished it in less than 4 minutes! I tried copying a 8GB movie to a flash drive and again, it said it would take an hour, then it said two hours, and the longer I let it go, the slower it got. But other times, it does complete the comparable task quite reasonably. Generally restarting the computer doesn't solve the problem, but letting it sit for a few hours does – which seems very strange. It would almost seem as if the computer gets tired.

    I don't think it stems from a RAM shortage? Monitering the ram usage confirms this. Small tasks like word processing are very efficient. I can multitask well also. Anything involving data transfer is terrible. My suspicion is a dying hard drive. I have repaired disk permissions and I have verified the disk in Disk Utility with no reported problems.

    However, I recently tried a Disk Speed test with Black Magic Disk Speed Test, and it reports write speeds of consistently 55-75 MB/s, but the read speeds sometimes spike to ~70 MB/s but always droop back down to less than 20 MB/s and generally they fall down to less than 5 MB/s! My 2009 Macbook with a 5400 RPM hard drive both writes and reads consistently at around 35-45 MB/S. Why might the iMac read so inconsistently and so much slower than the speed at which it writes?

    What do you guys think the problem is in particular? An old dying hard drive? Or something more?

    I'm thinking about buying either the Seagate 1TB SSHD or the WD Blue 1TB HDD and braving the replacement procedure with the help of the ifixit guide. I just don't want to go through all the trouble and be disappointed. Do you think that the HD is the culprit and that replacing it would be a worthwhile attempt?

    Attached Files:

  2. R2D2WD macrumors newbie


    Sep 23, 2014
    Hi there,

    Could you check if you have some ongoing background anti virus scans or software updates? Unfortunately, I would say that the drive may be failing, even though those changes in performance seem a bit strange and provoke some thoughts about other problem. Speed drop may be an indicator for a hardware issue, and, saying that your HDD is a bit old, leads me to the conclusion that it may be failing. If you have the option, do a data backup, format the drive and check again. I would confirm that it is not a cable issue. After that, if those speed drops still persist, I would consider a new purchase and the WD Blue is a good choice.

    Hope this helps
  3. mreg376 macrumors 6502a


    Mar 23, 2008
    Brooklyn, NY
    Sounds like your hard drive is way overdue for replacement. If you want to give your 2008 iMac an entirely new lease on life, and have it feel like a brand new machine, replace the hard drive with an SSD (any size depending on your needs), and upgrade the RAM to the max of 6GB. The consensus is that Yosemite screams with those upgrades, and I can tell you from experience that it's true. If you're going to go to the trouble of replacing the hard drive, it's ridiculous to install another spinning platter. And the RAM upgrade is so easy it's a no-brainer. Go to OWC ( for the correct RAM. You can get an SSD anywhere.
  4. Ray2 macrumors 6502a

    Jul 8, 2014
    I have the same iMac and it was displaying the same issues with its original 750 gb drive. A SuperDuper clone that would normally take 3 hours max was only 1/3rd done 11 hours later. Started it over and it was done in 3 hours. Also inconsistent write speeds to a brand new external.

    You probably need to replace the drive. I popped a 500 gb Crucial MX100 ($207) in it (offloaded iTunes and images to an external) and its been great ever since. I ran 2 scheduled clones a day until I got the drive replaced. Opening up the iMac is not all that bad. The I fixit and OWC's videos do a good job. Easier than a 2010 mini I had already been into twice, also stuck an ssd in it.

    As far as ssd's, don't expect a miracle. Its a much better user experience in that its more responsive. But I do heavy photo editing and occasionally video. Its still the same CPU.

    I also bumped ram from 4 gb to 6. Haven't noticed a bit of improvement with the additional ram running 10.8. I installed the ram 3 weeks ahead of the drive so nothing else had changed.
  5. nrubenstein macrumors 6502

    Aug 5, 2008
    Washington, DC
    Avoid the SSHD unless you hate your data.

    Personally, I would install a 256GB or 512GB SSD. That'll get you enough improvement in performance to make the machine feel pretty decent, especially compared to a 2009 Macbook Pro.

  6. ZVH macrumors 6502

    Apr 14, 2012
    You could test it with something like Scannerz or Scannerz Lite (http://scsc-online.Scannerz.html), but they cost money. Scannerz Lite is a simple pass/fail, Scannerz comes with a bunch of other tools, like Performance Probe that can point out in load monitoring mode what's eating up the CPU and graph drive performance.

    I'll be honest though, that sound more to me like it's good 'ol Yosemite doing stuff. Had it on one partition and it likes to bottleneck during the following:

    - mds indexing of the drive
    - Collecting system information
    - Just being a PIA

    mds indexes the drives for both Time Machine and Spotlight. When it kicks on it's extremely drive and CPU intensive. Typically once it gets done doing it's regular indexing it finally shuts up, but sometimes that can take half a day on a system with a lot of information on it.
  7. caaalebbb thread starter macrumors member


    Mar 15, 2011
    Thanks for the advice. How do you suggest confirming that it is not a cable issue? Do you mean the SATA cable?

    I will avoid the SSHD then. My worry about a SSD is that I use my iMac as a DLNA server to stream movies and music onto my TV over the network. So a SSD (within my price range) would not be big enough to store my files. I could get an external hard drive (I'm assuming I'd use firewire), but I'm not sure if I could still stream over the network off of the external hard drive or if I'd run into some streaming bottleneck. What do you think?

    Thanks for the input, everyone.
  8. nrubenstein macrumors 6502

    Aug 5, 2008
    Washington, DC
    Even USB2 is more than fast enough to stream over the network. You'll need a keep alive utility to prevent the disk from spinning down, but other than that, no biggie.
  9. caaalebbb thread starter macrumors member


    Mar 15, 2011
    Would a firewire external HDD be preferable for my purposes? (streaming over the network)

    EDIT: Also, I never use my CD drive in this iMac. Is it possible to replace that with a hard drive and have two internal hard drives? Or is that quite an advanced procedure (if it is even possible)?
  10. Intell macrumors P6


    Jan 24, 2010
    A FireWire 400 drive would be slightly faster than a USB drive and use less CPU cycles to access it. A FireWire 800 drive would be best at a little over twice the speed of USB 2 and double that of FireWire 400.
  11. caaalebbb thread starter macrumors member


    Mar 15, 2011
    Okay, so I am going to buy a new 1TB HDD (I cannot afford to go SSD+External).

    I have a question though. I do not have a wired keyboard; my current keyboard is apple's Bluetooth wireless keyboard. I used a friend's wired keyboard once so I could use the appropriate startup key combinations when I needed to boot from a USB stick, but they are not around anymore. I have tried all kinds of things and I cannot do any of the startup key combinations with this wireless keyboard!

    I was hoping to install OSX Mavericks (via USB stick) on the new blank HDD (I started having problems shortly after I installed Yosemite). Because the iMac will not be able to boot from the HDD (because the HDD will be blank), will it automatically boot from the USB stick? And once it does boot from USB, will the bluetooth keyboard work as I go through the install process? Or do I have to get ahold of or buy a wired keyboard? And, if so, what is the cheapest wired keyboard that will be compatible to get the job done?
  12. Brian33 macrumors 6502a

    Apr 30, 2008
    USA (Virginia)
    It sounds like you're going to save some $ and go with a 1 TB internal hdd, but I have the exact same machine as yours and I thought I'd answer this question in case you ever want to try it in the future:

    Yes, it's very feasible to have two internal drives in this iMac. I replaced my original 320 GB hdd with a 2.5" SATA SSD and removed the optical drive to install a 1 TB, 2.5" SATA HDD (using an adapter, see below). Then I created a Do-It-Yourself Fusion drive with the two. It has worked wonderfully well, under OS X 10.8.5 Mountain Lion.

    Here are some details: this machine has a SATA II (3 Gbps) connection to the original HDD bay, but a PATA (sometimes called IDE) interface to the optical drive bay. That's why I put the SSD into the HDD bay, to take advantage of the faster SATA II speeds, and the new HDD into the optical bay, since the PATA is slower. PATA/IDE came in many different speeds (see Wikipedia) and I was never able to determine for sure which version my iMac has, but I decided it's most likely one of the later (fastest) PATA revisions and thus I think would not significantly slow down the new HDD.

    The PATA adapter cost $40 at (here). You can do the work yourself; I used the excellent guide at iFixit. Note that you'd need a 2.5" HDD if you put it in the optical bay.

    One caveat: I used a probably ridiculously large SSD for a Fusion drive: a 512 GB (not my original plan and a boring story about how I ended up with it). Perhaps this has a bearing on how supremely happy I am with the results, BUT, I think even going with a 128 GB SSD / Fusion Drive would give great results for this machine. So, if you could afford a 128 GB SSD and the admittedly pricey PATA adapter, you might consider it!

    This is my daily use machine and I still love it. BTW, I use it as a PLEX server to stream movies to my Roku box, which I guess would be similar to your DLNA usage scenario, and it works great. Good luck!


    Oh -- sorry I can't answer your questions about the wireless keyboard, since mine is wired. However, I believe it is possible to use an Apple wireless keyboard even for the boot-time keyboard sequences. I don't know the details, though.
  13. caaalebbb thread starter macrumors member


    Mar 15, 2011
    I backed everything up onto an external HD. This was an incredibly frustrating process. I don't have a lot of data – I have around 100GB of data, but I was only able to transfer around 5-12GB of data at a time as the transferring process would get gradually slower until it essentially came to a halt. I often would have to force the computer to shut down at that point because it was unresponsive. After a few hours I was able to go at it again, transferring another 5-12GB. I kept doing this until all my data was on an external hard drive. I always would have to wait a few hours between transfer sessions (a simple restart would do nothing – it would simply take forever to start the OS).

    At the end of this whole process the iMac was even slower than it was to begin with! After I safely had all my files on my external HD, I booted from a USB stick and wiped/reformatted the iMac's HDD and did a clean install of Yosemite. This was a very long process, but it finally installed. However, even with a completely clean install, without even installing any applications or putting any files onto the iMac, any kind of loading was incredibly slow (especially maneuvering through the Finder). Internet browsing wasn't so bad. General processes would execute smoothly, but there is generally a terrible lag before they start executing.

    I'm guessing the HDD is the culprit. Now that I have my music library and movies on the external HDD, I realize that I like being able to plug in my data to either my iMac or my Macbook.

    So I've decided to get a small (120GB or 128GB) SSD to replace the HDD in the iMac, and then keep all my media on the external HDD so that I can use that with my Macbook as well. I might also go back to Mavericks.
  14. FrtzPeter macrumors member

    Aug 11, 2014
    The HD may not be the problem. Like the ZVH guy, I use a product called Scannerz and just a few days ago they (SCSC) sent me an e-mail about the problems users might encounter with a little feature in Mavericks and Yosemite called "App Nap." App Nap was addressed in the product (Scannerz) release notes but apparently people were overlooking it.

    App Nap causes an application to, literally, go to sleep and stop working until the application is made foreground. This is supposed to be an energy saving feature but apparently a lot of people aren't aware of it. SCSC pointed out that this might cause stuff like downloads and software updates to just stop, and it's a part of both Mavericks and Yosemite.

    If you ask me, Apple did a really stupid thing putting that in. If they had a dialog pop up and tell people "I'm about to put your app to sleep" or something like that at least people will be aware of it, but instead it just happens without you knowing about it. If you're using Mavericks or Yosemite, that might be the problem.

    Here's a link that will tell you how to disable it system wide:

    If you want to disable it on a single application only, you right click on the icon for the application and when the side menu shows up, click on "Get Info...". There will be a field called "Prevent App Nap" and you need to check on it.

    I don't know if this will help you, but I ran into this problem myself doing downloads and since disabling App Nap system wide it's no longer a problem.

    Another thing Yosemite does on a fresh install is start gathering all kinds of information about your system and it will also start indexing all the drives with Spotlight. That will slow you down too. Finally, Yosemite has lots of bugs.
  15. caaalebbb thread starter macrumors member


    Mar 15, 2011
    Hey! Thanks for the heads up on this! I'm going to try preventing App Nap and I'll report the results (if any).
  16. caaalebbb thread starter macrumors member


    Mar 15, 2011
    I think I have (finally) confirmed that my HD is in fact the main culprit, via an app called 'SMART Utility'.

    Attached Files:

  17. FrtzPeter macrumors member

    Aug 11, 2014
    If that's reporting correctly, then yes, your HD is failing. However a lot of those SMART utilities are basically using a free software package called smartmontools with the tool called smartctl embedded in it. If they don't keep it up to date, and from what I can tell, a lot of them don't, it may misreport.

    If your drive is still normally formatted you can check SMART status using Disk Utility as follows:

    1. Open up Disk Utility

    2. When it comes up, click on the icon for the entire disk you want to check (not a volume, the volumes are indented with respect to the entire disk)

    3. In the upper left corner, click on the "i" in a blue circle

    4. A table will come up showing all the SMART parameters as well as the status. If SMART is failing it will say so. I'd think you could compare the output of that with SMART Utility, just in case it's reporting incorrectly. There are a lot of posts on this site about people using SMART Utility and Drive DX (both use smartctl) and if it's version of smartctl is outdated it's reporting a failure (or success) when there isn't one.

    IMPORTANT CAVEAT: The Disk Utility SMART reporting only occurs for normal HFS volumes. For reasons known only to God, Apple is now using Core Storage as a default partition for Yosemite, so you'll need something else if you want to get SMART status. If the volume existed beforehand and you didn't repartition it may still be in HFS format.

    Good luck.

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