Hard Drive Apple iMac G5 Repair Story

When an Apple iMac G5 locks up on you, it might mean the hard drive is bad.

Many folks have contacted me over the years about their Apple iMac G5 problems they have been having because of bad motherboards or power supplies. Well, I thought I would share a story of my own, in regards to trouble shooting a bad iMac G5, in the hopes that it might help some of the folks out there in Apple iMac Computer land.

I recently picked up a used iMac that was giving the previous owner fits, in that it would eventually, after some time of being turned on, would lock up on them and only show the Apple logo at startup with the little circle going round and round. The fans would start turning at full speed. Once this occurred, the only way to get it back up and running was a fresh load of the software from the DVD disk back on to the hard drive.

Prior to loading the software back on the hard drive, I had gone through the procedure of checking out the capacitors on both the motherboard and the power supply unit, but did not see any signs of capacitor trauma, as in; bulging, leaking, or blown capacitor bodies. When having an iMac G5, it is always wise to begin with a visual inspection of both the motherboard and the PSU. Refer to my write-ups on repairing the Apple iMac G5 motherboard and how to repair an iMac G5 power supply unit for complete details.

I tried resetting the PRAM (Parameter RAM) and also tried resetting the SMC/PMU [System Management Controller (Intel Macs) or Power Management Unit (PowerPC Macs)]. I also tried replacing the PRAM backup battery (Energizer 2032) that retains the small amount of nonvolatile RAM (NVRAM) for the PRAM. This is where the date and computer settings are stored when the computer is turned off. None of this made any difference on my iMac lockup problem. Here is a very good article overview of the PRAM and SMC/PMU failure symptoms and when to reset the PRAM and SMC/PMU.

Well, after repeated hardware tests, with no indications that any hardware was bad (so much for hardware tests), I pulled out the old Maxtor 250 GB hard drive and tried reformatting it externally and backing up one of my other iMacs to this hard drive using a USB connection and an external hard drive adapter. The backup was completed successfully, and I returned the hard drive into the original iMac G5 cassis, and it booted up. Well, this was only a short term success. The iMac locked up when trying to do a software update. I was thinking that the software might be locking up because it was installed on the other iMac and registered on the other iMac. So, once again I took a brand new Leopard software disk family pack, and tried loading it on the hard drive again. No luck on this software load either. It bombed out part way through the loading process and returned to the Apple logo going round and round on startup.

Well, I am not one to let a little Apple logo roadblock stop me from getting to my iMac computer land destination. So out I go to my local Frys store (Frys is a large electronics store on the West Coast and another 8 states) to find out the best deal on a serial ATA hard drive. I didn’t want to spend a fortune, and I wanted to get the best value for the money. I ended up purchasing a Hitachi 640 GB HD for around 70 dollars. I figured I could always use this drive on something else if it didn’t work to fix the problem on this iMac.

So, I brought it home, opened it up, placed the mounting brackets on the new hard drive, mounted it in the iMac, and buttoned the whole computer back up. I then placed the Mac OS X Leopard DVD install disk in the slot, turned it on, held down the “C” key on startup. I then used the disk utility to format and mount the hard drive. Then loaded a fresh installation of OS X Leopard, did the updates, and have been running terrific for three weeks or so with no problems. I even added a “matched set” of PC 3200 1GB memory sticks for a total of 2GB of RAM. Now, I am a bit jealous for my own original iMac G5 computer with Mac OS X Panther installed. I think I will upgrade my other 20 inch iMac G5 to Leopard too. But that is a project for another day, and I am told that you have to do a fresh install too. Which means backing up and transferring the files over to the new installation.

Well, for the time being I am on happy trails to you, until we meet again.

Update to article: 12/25/2010

Just last week, I had another iMac G5 computer with a Seagate Barracuda 7200.7 160 GB hard drive (Apple identification:  160GB C6SER 655-11109D “KA45304C7RT9A)   go out. I went to FRYs again and selected a 1TB Seagate drive (drive only, not boxed) and installed it. I had a problem that it would not show up with the Apple Disk Utility. However, when I used my adapter plug to plug it into a PC, the drive would display. I tried using the jumper to force it to a slower access speed, but it still would not show up in the iMac. I then took this one back and got another brand (Hitachi 500 GB hard drive only, not boxed) from Frys again, but this one was completely dead. It would not spin. It was an old drive that was the last one in stock. I took that one back also, and Frys confirmed that the drive was indeed dead.

However, I did find another Hitachi 660 GB SATA hard drive online at Frys that I did order. When that one came in, it plugged in just fine and showed up with Disk Utility, formatted, and loaded software with no problems.

I believe other manufactured brands internal drives will indeed work with the iMac G5s, I just have not been able to confirm which ones.

Jim Warholic


So what's really happened to the old HD? Bad sector? SMART failure? It seems that you're able to backup the whole harddisk signify that the hard disk was ok.

Jim Warholic

The hard drive failure was one that really surprised me. I was talking with someone else that thought the hard drive failure I was experiencing was with a slow read failure. The person was having random freezes on his mid-2007 20" iMac, and finally was able to run the proper Apple Service Diagnostic disk on it.

He mentioned in the email to me, "Everything was passing the rather extensive and strenuous tests, except for one drive test for slow read failures within the first 10 GB of disk space. AppleCare replaced the 320 GB hard drive three months ago, and I haven't had any more freezes."

He referred to his bad hard drive as, "a sneakily faulty hard drive." That refers to exactly what was happening on my particular HD also.

Jim Warholic

Well Jason, there is an old Murphy's Law saying that goes something like this, "If it isn't broken, don't try to fix it."

With what was happening to the iMac, in the way it was scrambling the hard drive information, I was concerned that something other than the hard drive was faulty. With my luck, I would have ended up with two down machines instead of one.

My main iMac was working properly, and I did not want to take a chance that something was going to happen to it. I always say, "It is better to error on the side of caution, than take a chance on something that was much too precious." Besides, if that hard drive didn't work in that machine, I would have used the HD anyways in something else. In the scheme of things, hard drives are dropping in price to the point that it is a good trouble shooting aid and a great insurance policy to have an extra one around, and try it, if you need it.

If I had tried the other drive from a good iMac, and I had lost software, or the operating system got corrupted, even if I have a backup (which I do have), then I would have had to reload the software on two drives and wasted a ton of time.

It is always wise to follow trouble shootings "best practices," and don't mess around taking foolish shortcuts. Unmarked shortcuts have a way of becoming long detours to your destination.

These are my words of wisdom for the day.

Take the smart road to success.


Sharon Graham

My local Apple store refused to replace my G5 hard drive because when they opened the case they found dust and "spores" in the case. Now I'm left trying to find someone locally to do it, or order a replacement hd and do it myself. So far, no luck in finding another repair person.
I appreciate your information and am looking at the diy route now, but the Apple rep I spoke to made it sound like I need some special tool to do this. I've replaced equipment in pc's before but this is my first Mac. Any helpful links, or information on that "special tool" so I can go at this with more confidence?

Thank you!

Jim Warholic

Hello Sharon,

Replacing the hard drive in an Apple iMac G5 is fairly easy to do. Apple provides a number of do it yourself iMac G5 hard drive replacement procedures to follow.

You really do not need a special tool for the iMac G5 HD replacement. However, I would suggest blowing the whole inside of the iMac G5 out before starting. Make sure the cooling vents and fins on the heatsink are all clear. Once the new drive is installed, then the DVD system install disk can be used to install the software. Also note that you can install OS X Leopard on the iMac G5 PowerPC models. If you have a newer Intel based iMac, you can install Mac OS X Snow Leopard on it.

It is important to note that the Intel iMac comes apart differently than the G5 PowerPC model. With Intel model being more difficult to disassemble, it also makes it more difficult to replace the hard drive on the Intel iMac too. I suggest taking a look at some videos online and even some of the pictures before you start on the Intel iMac hard drive replacement procedure.

Sharon Graham

Thank you, Mr. Warholic. I sincerely appreciate the links and information. The Youtube link on information regarding just opening the case is so helpful. I don't have money to waste, but do have to believe that I can do a better job on making this repair myself, rather than blindly trusting people who work on pc's for a living. If I fail, I've lost another $80.00 on a hard drive. If I succeed, I've learned how to successfully repair an expensive object that means a great deal to everyone in my family. The very fact that you provide this assistance online means people continue to have choices. I may be 56, but will not be intimidated by technology, thanks to your help. Thank you, again!


Thank you for sharing your story, Jim. I’m in the middle of the very same experience with my iSight G5. Initially, the first couple of “hangs” rebooted just fine, so I figured it was software corruption. Disk Utility failed to reveal any problems and I already had a recent full backup, so I wasn’t panicky. But then came the Grey screen problem you described. Integrity tests, diskwarrior and even a zero-out erase didn’t work presumably because the drive won’t remain reliable for the duration of the procedures and things hang. I’m not looking forward to the DYI solution. I repaired a 2004 17″ PowerPC imac and it was very easy getting in and out but my 2005 iSight version is a bit more complicated (dumbest. design. ever.) Anyway, thanks for the post. There is hope!

Jim Warholic

Hi Rob, I agree with your take on the iSight models being more complicated to dive into.

I’ve included some reference pictures and videos in my Apple iSight link for disassembly. It almost seems like Apple made it a pain in the rear on purpose to say with pride, that they didn’t need to have any exposed screws holding these Apple products together. In my opinion, from a service standpoint, and the time required to just dive into it to check and/or replace different hardware components, is extremely time consuming on the iSight models. That’s probably why Authorized Apple Service and other third party Apple repair shops need to charge the higher fees on these iSight repairs. So, it makes financial sense to learn how to do it yourself in most of these iMac computer problems.

Best of luck to you.


Jim, thanks so much for the follow up post and link. Today, I removed the after-market RAM module and booted the iSight from an external drive. I then dismounted the internal. I set the power settings to never sleep or spin down and also set the screensaver to something that would require a little processor usage. I thought if the iSight ran fine for a day or two from the external drive, I could feel confident I isolated the problem to just a failing internal HD. Within an hour the machine recovered from two spontaneous SBOD before I decided to shut it down. Temp monitors showed normal readings at the time of the hangs. Because the internal HD was not even mounted and the machine still froze, I am pretty sure it is a capacitor problem. I plan on doing a visual inspection next….



Thank you for sharing your success story online? I have a question on my iMac G5. FYI, I bought my Mac in 2005. I would be very appreciative of your help by giving me some geek tips. Today, I think my machine is down. I’ve been spending hours with Google online, shared by forum short cut tricks, with no luck, and also, I’ve replace battery with a new battery back up. When I start it up, it seems to start up fine, but it won’t show up my monitor screen properly, and then after 30 seconds the fan starts sounds crazy noise from the back vent. My warranty is no longer covered. Jim any ideas about this? Hope you can help me.

A million thanks

Jim Warholic

Hi Joe,

I would always start with a visual check of the MOB caps. Then proceed to an internal visual inspection of the PSU caps. Refer to my various articles on the Apple iMacs for complete details of what and how to check these areas. Bottom line, I suspect you have bad caps.

I have brand new caps for sale at my online eCommerce store.


Maybe you can offer some guidance for me.

20″ iMac G5 (iSight)

Sporadic powering off. Ran hardware test, showed “Mass Storage” error.

Replaced hard drive.

The powering off issue stopped but running Software Update after fresh system install would result in freezes during updating(Had to reinstall system 2 or 3 times, always the same, just rampant instability).

Now running hardware test again, 3rd time straight, its showing “Mass storage” error still. Error code (2STF/8/3:S-ATA Bus 0 – Master)

Is it possible this is all due to a bad power supply?

I would assume logic board but it hasn’t showed and error in hardware test yet even after running the extended test 5 times in a row.

Is it possible to replace the SATA connector on the MOB?

Thanks for any help.

Jim Warholic

Hi Kevin,

Powering off problem leads me to believe that it probably is a PSU problem. If a voltage is flaky, it can cause all types of random problems. I would double check your voltages. Refer to some of the other articles I have written about the Apple iMacs.


I have a similiar problem to Kevin.

My iMac “Core 2 Duo” 2.4 20-Inch, Lucille, also has been powering off lately. She really doesn’t power off so much as reboot – screen goes black, 3 second pause and then restart.

Tried self-diagnostic and then took her into genius bar after she suffered 4 fainting spells in a row last night while working on a simple Googledocs.

Of course, she is performing like a diva for them and won’t replicate the problem. I agreed to let them change the powersource for $160 and left her during a stress test. They called back and said she passed the stress test, they cleaned the powersource of dust and the only issue they see is an error message in the hard drive but nothing specific. I could replace the hard drive for $360 and hope that solves it.

I am going to pick her up and bring her home. If she faints one more time, I am taking her back for a hard drive replacement. Is this the right course of action?

Jim Warholic

Hello Katie,

Those divas are a real pain.

First off, 360 dollars sounds awfully expensive for an internal hard drive. You could try a brand new 1TB HD from Amazon (see above) for under $90.00.



Hey Jim,

What is the name for the kind of hard-drive pictured in your post? I’m having a hell of a time trying to find a HD with the same terminals (connectors?) as the one I’m taking out of my iMac. The terminals on mine are identical to the ones in the image above. Thanks in advance for your help


Jim Warholic

Hi Lane,

The picture is of a generic 3.5 inch HD with a SATA (Serial ATA) connector. I am told that any brand SATA drive will work with an iMac G5, though I can not confirm this.

Sloan Jones

My grandson recently gave me an imac g5. My grand son had not used it for several months, but he stated that it worked fine; the last time he used it. My daughter then transported it 300 miles in her car.

When we tried to fire it up all we got was an Apple logo and a spinning wheel. We have run all the tests we could find with no results. If I hold down the Option key at turn-on, I get a blue screen with the Disc Drive Logo. I can insert and eject the CD from the Key Board. The mouse controls the arrow, but if I use the mouse to try and play the CD, the screen reverts to the Apple logo and spinning wheel. HELP

Jim Warholic

It almost sounds like the software on the hard drive has gotten corrupted. You might try to boot from the software disk to see if at least you can get to that point. Then, you might have to do a reinstall of the system software. By the way, OS X Leopard version 10.5 (not Snow Leopard) can be installed on the iMac G5 PowerPC computers. If there is important information on the disk, you might want to actually put in a new cheap hard drive, then reload software, then gather the information from the old HD using a hard drive adapter.

Jim Warholic

Maybe you have other issues. Either the PSU or the main logic board could be at fault. Take a look at some of the other Apple articles I wrote. The other thing that you have to do to boot from the DVD software disk is hold down the “C” key when turning it on. If it still does not recognize the software disk at that point in time, then something else is wrong.


Okay so my iMac G5 PowerPC with Tiger just stopped on me. It does the grey screen thing and I can hear the fan, but right before this started the sound went then the icons went so I restarted it and that’s when the nonsense started… does this sound like the hard drive?

Gary in NYC

Jim, thanks so much for this write-up. My sister has an iMac G5 that I upgraded with 2Gb of memory last year (she had a paltry 512Mb!). She was thrilled with the improvement, as she does a lot of work in Photoshop and Illustrator. Anyway… her apartment suffered a power outage and I have no doubt that her iMac was in standby mode when it happened. These old hard drives don’t do too well when shut down abnormally. Her problem is that the operation system won’t fully load. It tries to find a certain driver file and can’t, then hangs up with the gray screen.

My sister took it to Apple and they laughed at her. LAUGHED! “This old thing? It’s 6 years old! You need a new one.” Bah! The arrogance. It was working fine for her needs before this problem happened. Next, she took it to a local computer repair place run by some kids and they instantly saw an opportunity to take advantage. Thankfully before she committed to doing anything, she asked my advice. I called up that shop… and they could not answer my technical questions straight forwardly, and when pressed, they’d scramble back to “well, the hard drive is bad anyway”. Other basic questions were not properly answered and so, as the robot in Lost In Space used to say, “Danger, danger, warning, warning!” I had her get the computer back. I scoured the Internet looking for bits of information and yours is the best I’ve found.

I’ll be checking out her computer in person this weekend. I will definitely examine the mother board and PSU for issues, as you’ve outlined. I’m very much hoping that the scope of her problems are relegated to the hard drive. I’ll see if I can locate a few of the Hitachi models you’ve mentioned. At this point, in 2011, are there any other 500-750Gb drives worth looking at for this computer? Any particular ones to stay away from? Thanks!

Jim Warholic

I would take a look at the feedback using Amazon’s website. Look specifically for hard drives that have been used in the iMac. I tend to stay with what I know works. However, I am of the opinion that there are probably other hard drives that will work. Here is a search on Amazon for hard drives for iMac G5. I would read the reviews carefully for iMac related comments. You can use your browser’s “find” function to find the word iMac in the web page text. Worst case scenario, you should be able to return the drive to Amazon if it does not work.

Glen Green

Hi Jim
I have a 20 inch G5 isight. It will not boot, not even from the disc. After the tone, it opens straight into open firmware, with a scrolling message reading “default catch,code=1800”. Any idea what may be causing this?


Jim Warholic

It is possible that it still could be the hard drive even when trying to boot from the CD/DVD. I have seen a similar thing, where the hard drive was actually holding down the machine from booting, even when trying to boot from the CD/DVD. Not sure why that would be the case though. Depending on the exact model you have, (whether it is a PowerPC or Intel version) will determine how easy or difficult it is to remove the hard drive to see if it is faulty. Refer to the following Apple Manuals for disassembly instructions of your particular model.

Here is something I found online concerning not being able to boot. Can’t Boot: DEFAULT CATCH!, Code=1800


Aloha Jim,

I have a 2005 iMac G5 17 inch monitor (iSight) that I haven’t used in years. The problem is when powering on I get a black screen. Tried resetting the PRAM, same results, black screen. When I first took it in for repair, Apple quoted me over $900 to repair it. I said forget it and bought a new iMac G5 20 inch instead. This one has been working well ever since.

My 2005 iMac has been sitting in its box all these years. In your opinion is there any hope in getting it repaired? Should I even bother? I imagine it will cost more today to get it repaired.


Jim Warholic

Hello Susie,

Aloha reminds me that I would really like to get back to Hawaii some time.

I would say that you should at least try to inspect the inside of the the computer and PSU for bad capacitors. Refer to the Apple manuals for instructions on how to disassemble.

Also, refer to my other Apple articles for more information on what to look for in the way of faulty logic cards and PSUs.


My sisters Imac G5 2ghz was cutting out. Looked like a power failure at first. Did all the usual checks and all power supplies seemed fine and secure. Just for the hell of it I replaced the hard drive with a 320gb I had lying around. Instead of doing a clean install (didn’t want to lose her information and settings) I cloned the old (dodgy) hard drive using firewire and target mode to the imac. Also repaired permission and disc just to be precise. Machine works perfect now, and her desktop and settings are identical to when she gave it to me. The old hard drive must have some power issues, what I dont know, but it was causing a power failure in the machine.
Hope this helps someone.

Jim Warholic

Thanks Jem for sharing. Yes, I do think there are times when the HD can cause weird issues related to the whole computer in general.

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