Hi Will and everyone else. I don't know if anyone cares to keep on having an old 2007 24" iMac up and running, I just hate to dispose things and contribute to e-waste. So as I write this on my 2007 iMac which I have successfully been able to upgrade to MacOS 15 Sequoia, yep MacOS the latest version as off 10/2024, I wonder if I joined the discussion way to late. Anyway, Im facing some issues as posted before, the replaced T9500 is being reported as a 700Mhz Core Duo but powermetrics command reports both CPUs running at 350% at 2.6Ghz (which is what it is supposed to work at) so I don't know if the firmware just reports it as 700MHz overclocked at 2.6Ghz. I replaced the T9500 as well as the HDD for an SDD from OWC and it wasn't until I disconnected the original thermal sensor and installed OWC's one (which is part of the disc SATA connector) that the iMac booted again, before I only got 1 led near to the memory bank lighted up. Now Im wondering if the original thermal sensor needs to be plugged in also, according to OWC documentation, their thermal sensor should make the fans work "at normal speed", which as also reported, are running as a leaf blower and btw the SMC can't be read. Overall Im happy with the iMac been able to run latest browsers and the MSOffice suite with decent response.
If any one is curious, I used the OpenCore Legacy Patcher to upgrade the OS. Not a straight forward process, had to install Monterey first and then upgrade through Apple's System upgrade process (system preferences) and run OCLP post installation root patching a couple of times.