iMac Early 2008 running El Capitan via USB stick - screen frose watching streaming film in Chrome

[cooperd]

I have a 24" iMac early 2008 running El Capitan direct from a USB stick. Its a little slow on booting etc. but this mac is in the bedroom and I just use it to watch the likes of Netflix/Amazon Prime in bed. It does nothing else.

It has been running fine for months setup like this. Then a few nights ago whilst watching Netflix in Chrome the screen froze. Audio continued. I was unable to quit or force quit and as I was running in full screen I had no option but to hard power off the imac.

Then since then I've not been able to get the imac to boot. It always freezes during boot at some point whilst the progress bar is moving up. It never completed the progress bar.

I then set the PC to boot from its internal HDD which has Mountain Lion installed on it. Again the same issue, so I didn't suspect the USB boot drive (I have since wiped this).

Other things I tried - I could boot into safe mode from the USB stick fine.
Booting into recovery mode any disk selected came back fine using disk utility
Booted from Memtest86 USB boot drive and ran full diags - no issues detected
Booted from Apple Hardware Test DVD and ran extensive test and also came back with no issues detected.

At present I have managed to upgrade the int HDD from Mountain Lion to El Capitan, but again I could only do this in safe mode.

I've run smc fan control to just up the fan speed to see if heat was an issue and also whilst booting into safe mode in Mountain Lion I ran a temp app that I had installed years ago and all temp sensors were showing anywhere between just over 30c up to around 50c (this highest temp was the power supply sesor).

Does anyone have any idea? I was hoping to keep this imac for watching online moveis etc so didn't need the expense of buying another imac to then move my main machine to the bedroom to use for watching online movies.

This early 2008 imac 24" has the Core 2 Duo 2.8 Penryn processor (E8235), 4Gb RAM and the ATI Radeon HD 2600 PRO GPU.

Any help is appreciated.

NOTE: I have run through all types of reset for PRAM/NVRAM, SMC etc.

 

[herrdude]

Wouldn't a Firestick or Roku be MUCH easier?

Did you reset the PRAM and SMC? Then log into recovery, run Disk Utility and First Aid. Why not install SSD? Running an OS on a USB is not the best use of your computer...

EDIT: I just saw your note about PRAM. How about going through Internet Recovery and doing a clean install?

 

[cooperd]

Wouldn't a Firestick or Roku be MUCH easier?

Did you reset the PRAM and SMC? Then log into recovery, run Disk Utility and First Aid. Why not install SSD? Running an OS on a USB is not the best use of your computer...

Yes. See the last entry in my initial post.

Installing an SSD will make no difference at present. The issue is the machine is freezing in any instance, except in safe mode.

I have since installed a clean install of El Capitan onto the internal HDD. The issue sill exists! I'm at a loss. Maybe the only use the machine now has is to be slod for spares (display panel, power supply).

 

[DeltaMac]

2008 iMac cannot boot to Internet Recovery - too old! That feature did not appear until 2011, and Apple updated firmware to support internet recovery on 2010 Macs, but nothing older.

I was surprised when you said that you were able to update the internal drive to El Capitan, as the symptoms make me think it won't boot good enough to install another system. BUT, that's assuming that the reboot to complete the install worked... Did it work good enough to do that final reboot into the system the first time? Or no boot at all during the upgrade?
Seems like a failing video card, but that should also fail a hardware test. At least, I would expect a hardware test to fail.
Then, should be RAM, but you say memtest passes (?)

I would try a test from an intermediate OS X that should support your iMac very nicely, such as 10.10 (Yosemite), or even 10.8 (Mountain Lion). Booting from a clean system, with no installs past the basic system, other than system updates. I keep a drive that has multiple partitions, each with different systems that I use for boot troubleshooting -- issues such as what you are having.

Any reason why you couldn't just wipe the hard drive, and reinstall a fresh system (whatever you might have as a choice), and use that to check for booting?

 

[cooperd]

2008 iMac cannot boot to Internet Recovery - too old! That feature did not appear until 2011, and Apple updated firmware to support internet recovery on 2010 Macs, but nothing older.

I was surprised when you said that you were able to update the internal drive to El Capitan, as the symptoms make me think it won't boot good enough to install another system. BUT, that's assuming that the reboot to complete the install worked... Did it work good enough to do that final reboot into the system the first time? Or no boot at all during the upgrade?
Seems like a failing video card, but that should also fail a hardware test. At least, I would expect a hardware test to fail.
Then, should be RAM, but you say memtest passes (?)

I would try a test from an intermediate OS X that should support your iMac very nicely, such as 10.10 (Yosemite), or even 10.8 (Mountain Lion). Booting from a clean system, with no installs past the basic system, other than system updates. I keep a drive that has multiple partitions, each with different systems that I use for boot troubleshooting -- issues such as what you are having.

Any reason why you couldn't just wipe the hard drive, and reinstall a fresh system (whatever you might have as a choice), and use that to check for booting?

The upgrade when like this:

Mountain Lion that was always on the internal HDD did boot successfully once.
Whilst in ML I installed the El Capitan installer app and started the install.
When it did it's first reboot it got right to the end of the progress bar and then looked like it had hung.
So I powered off on the power button and then booted to safe mode where the install finished successfully all under safe mode.
So I now have EC installed, but to boot to it I have to boot to safe mode.

I hadn't thought of the graphics card...I would have thought if that was faulty it wouldn't display anything. Is there anyway it can be tested?

I doubt there's no chance of being able to get a replacement GPU now for a 12 year old iMac?!

Yes, RAM ran the full suite of Memtest tests all ok.

 

[Fishrrman]

Seems to me that you have something that has failed on the GPU.

This would explain why it might boot in "safe mode" ONLY.
That's because when you boot into safe mode, extensions are disabled. And I'm thinking that [also] when you boot into safe mode, the computer is NOT USING the full "dedicated portion" of the GPU, but rather is using either a very limited part of the GPU, or relying on internal (i.e., non-GPU) graphics routines of the CPU itself.

At 12 years old, this probably isn't worth fixing, even for limited usage.

Just wondering...
IF you boot into Safe Mode all of the time, can you still watch Netflix/Amazon Prime that way?

If that's the case... I'd just "go with what works" and live with it.

Or... you might look for a used 2012 Mini to take its place.

 

[DeltaMac]

What is the result if you boot to your El Capitan installer, Reinstall El Capitan, then wait it out?
This is just a reload, so don't be concerned about erasing or formatting. Just reinstall as it is.
Make sure that you don't have any external drives, other than the external bootable El Capitan installer.
Give it time to complete the install. If you get the progress bar, and the install appears to hang - don't get impatient.
On this old Mac, I might give up after no progress for 2 full hours.

You can probably find replacement video cards on eBay. Apple's part number for exact replacement is 661-4663, and the (more desirable) upgrade card is Apple's part number 661-4664.

This site has those for sale, but shows that none are in stock.

661-4663 - Video Card, MXM III , M76XT+/256MB, GDDR3, iMac (A1225)

661-4663 - Video Card, MXM III , M76XT+/256MB, GDDR3, Apple Service part replacement for iMac (A1225) We carry parts and tools for all Apple and Amazon Kindle models.

www.powerbookmedic.com

Might be worthwhile contacting that company directly.
(Do you want to spend that much money, with the possibility that something else may fail? It's "elderly" hardware, and maybe ready for full retirement )

 

[cooperd]

Seems to me that you have something that has failed on the GPU.

This would explain why it might boot in "safe mode" ONLY.
That's because when you boot into safe mode, extensions are disabled. And I'm thinking that [also] when you boot into safe mode, the computer is NOT USING the full "dedicated portion" of the GPU, but rather is using either a very limited part of the GPU, or relying on internal (i.e., non-GPU) graphics routines of the CPU itself.

At 12 years old, this probably isn't worth fixing, even for limited usage.

Just wondering...
IF you boot into Safe Mode all of the time, can you still watch Netflix/Amazon Prime that way?

If that's the case... I'd just "go with what works" and live with it.

Or... you might look for a used 2012 Mini to take its place.

Thanks. Safe mode only for watching Netflix etc is a non starter as Chrome under safe mode is just waaay too slow. Thanks though.
[automerge]1589831062[/automerge]

What is the result if you boot to your El Capitan installer, Reinstall El Capitan, then wait it out?
This is just a reload, so don't be concerned about erasing or formatting. Just reinstall as it is.
Make sure that you don't have any external drives, other than the external bootable El Capitan installer.
Give it time to complete the install. If you get the progress bar, and the install appears to hang - don't get impatient.
On this old Mac, I might give up after no progress for 2 full hours.

You can probably find replacement video cards on eBay. Apple's part number for exact replacement is 661-4663, and the (more desirable) upgrade card is Apple's part number 661-4664.

This site has those for sale, but shows that none are in stock.

661-4663 - Video Card, MXM III , M76XT+/256MB, GDDR3, iMac (A1225)

661-4663 - Video Card, MXM III , M76XT+/256MB, GDDR3, Apple Service part replacement for iMac (A1225) We carry parts and tools for all Apple and Amazon Kindle models.

www.powerbookmedic.com

Might be worthwhile contacting that company directly.
(Do you want to spend that much money, with the possibility that something else may fail? It's "elderly" hardware, and maybe ready for full retirement )

Many thanks for the part no's etc. Maybe 'may' find a second-hand one for sale on eBay that I might take a punt at.

As you are aware of the part no's. I have another Q. Do you also know if there is a direct WiFi card replacement that would allow me to then upgrade to High Sierra using dosdue1's force upgrade? {Just a shot in the dark that you may}

Thanks again.

 

[DeltaMac]

...
As you are aware of the part no's. I have another Q. Do you also know if there is a direct WiFi card replacement that would allow me to then upgrade to High Sierra using dosdue1's force upgrade? {Just a shot in the dark that you may}
...

I suppose the wifi card is not supported on the HiSierra system? You MIGHT try contacting @dosdude1 about that... and I do know that dosdude1 sometimes replies to threads here that are interesting to dosdude1. Maybe you will get lucky.

 

[Fishrrman]

Rather than spend any money on a 12-year-old iMac that may or may NOT work after you try swapping out components, again -- for light duty in the bedroom -- I'd suggest looking for a late 2012 Mini. Very capable little Mac that can now be had for good prices.

 

[cooperd]

Well thank you all for your input.

I have the iMac back up and running. Not sure if it was the GPU, but I did bake it at 200c for 10mins on alu foil balls with copper coins on both the GPU and the other big surface mount chips.

I am wondering if it may have been the thermal paste that was the real issue.
Owned this iMac from new so it's never been replaced. Paste on the GPU heat sink was very dry, but the white sticky pads/stuff on the other large surface mount chips wasn't looking good at all, almost worn away/bubbled/melted.

Unfortunately I didn't have any thermal pads in lockdown, but just one oldish tube of thermal paste, so used that on both the GPU and the other chips. It wasn't the thickest, it was quite runny, so not ideal. I replaced the heatsinks very carefully enough as to not push the paste all over the place and off of the GPU and chips. Maybe if it doesn't stay operational for that long I may order something more appropriate from the web. Any suggestions?

Have reinstalled El Capitan from fresh onto the internal HDD. Not that bothered of running it from SSD as I didn't want to spend any more on a 12 year old iMac.

I have purchased a copy of TG Pro to monitor heat though... interestingly I've noticed that the power supply proximity sensor gets the highest temps at around 70c...so I've set TG Pro to switch all fans on to 50% when it detects it to be at 65c.

The PSU board in this iMac is the only thing I've ever replaced as the original one went pop quite a few years ago....not sure if this had anything to do with the iMac breaking down the other week.

For now it's running so I'm happy. Thanks again!