This is what he wrote to me. I hope someone can help him:

"The basic problem I am having is that my computer (late 2009 iMac with OS
version10.13.6) boots fine and runs flawlessly for a while. It then begins
to slow and then freezes. Some of the particulars are as follows. This
occurs whets her the browser is Google Chrome, Safari, or Firefox. The
slowdown begins with the picture pausing while the sound continues
normally. This continues until both the sound and picture are frozen. This
process always occurs and begins anywhere from 15 minutes to an hour after
startup. When I close and reopen the app, such as Pluto TV, the freeze is
momentarily melted and the freeze process is repeated. This period is
considerably longer when I close and reopen Google or Safari. It is even
longer when I restart the computer. Finally it is even longer when I shut
down the computer, wait a couple of minutes and boot up again. My initial
thought was memory. So I increased the RAM from 4 to16 GBs. No solution. I
reinstalled the system with no effect. I followed the freezes with my
Activity Monitor app and there was no significant energy impact. The CPU
load and the memory show no significant pressure. I feel there is a setting
that i clicked on that is loading information but not removing it or
transferring it to the hard disk or somewhere else. This problem continues
to puzzle me and the freeze up always seems to occur at just the wrong time."

On my 2009 iMac I have seen that kind of freeze three times since I purchased it 10 years ago. Twice it was associated with a failing hard drive, the first time under warranty. The other time was due to a failing video card. Those would be the first things I would check.

yes, have him boot from a new external drive (probably via FireWire?) and see if it works better.

Also use a utility to monitor CPU temperature, it could be full of dust bunnies and heat kills things.

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yes, have him boot from a new external drive (probably via FireWire?) and see if it works better.

Also use a utility to monitor CPU temperature, it could be full of dust bunnies and heat kills things.

Both of these. And, if the external is the issue, replace the original HD with an SSD. That's a near trivial job in those laptops.

On the other hand, if he's already replaced the HD, the problem is very likely to be the ribbon cable connecting the HD to the mother board. They are very fragile. So, be careful if replacing the HD.

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Embarassing myself on the Internet since 1978.

The goo That goes between the CPU and the heat sink may have dried up, And need to be replaced.

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raz

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space-time
yes, have him boot from a new external drive (probably via FireWire?) and see if it works better.

Also use a utility to monitor CPU temperature, it could be full of dust bunnies and heat kills things.

Both of these. And, if the external is the issue, replace the original HD with an SSD. That's a near trivial job in those laptops.

On the other hand, if he's already replaced the HD, the problem is very likely to be the ribbon cable connecting the HD to the mother board. They are very fragile. So, be careful if replacing the HD.

Not a laptop, unfortunately, so probably not trivial.

I have a completely dead 2009 iMac sitting around taking up space as we wait for e-recycling to (we hope) resume.

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My life goes smoothly and in regular intervals

Slowdowns like that are frequently from excessive drive activity and often point to a failing boot drive.

Have your friend run SMART Utility to check the drive.
[www.volitans-software.com]

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Integrated or discrete video card?

If it has the latter that's what I'd suspect (after the hard drive)

For general browsing even USB 2.0 is fast enough for an external SSD to be useable...try cloning the internal HDD to an external SSD and reboot from the external.

I just upgraded a relative from a 2006 iMac (USB 2.0) to a 2014 iMac (USB 3.0) and plan on doing the above.



Edited 2 time(s). Last edit at 10/21/2020 10:32AM by Bill in NC.

It does it on a new HD, the original HD, and a USB thumb drive.

Malware scan:
[www.malwarebytes.com]

Remove all login items from System Preferences > Users & Groups.

In Activity Monitor, look under the "Disk" tab and monitor disk activity, bytes read and written.

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Only occurs when running the browser?

If it's not hardware as per above, probably malware?

Has the user tried a different account?

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anonymouse1
Only occurs when running the browser?

If it's not hardware as per above, probably malware?

Has the user tried a different account?

I think he has mentioned it has happened while watching YouTube. I'll ask him.