Unusual strange issues after upgrading e8400 to Core 2 Quad Q9650

[petals]

Hi !
I ran OSX  Sierra 10.12.6 on EP45-DS3L F6 8Mb 800 MHz Core 2 Duo E8400.

I need that setup keep working as still had some set of projects that need Logic, FXPX and customized plugin set that impossible to upgrade to the modern OS.

Couple of days before I upgraded CPU o Intel Core 2 Quad Q9650, then ran into weird problem. 

 

In my case, it seems Power management doesn't work at all. 

At first it was OK but then, can't identify now exactly after I clear CMOS (had problem with a wireless mouse/keyboard) or experimenting with NullCPUPowerManagement and system definition, the state of system currently as follow:

It boot OK then CPU starts to work to max power, temperature rise up to 60% within 2-3 min, then it stuck and goes to reboot. 

I tried different version of BIOS from v6 that was originally to f9 and f10 that is recommended to Q9650, no results.

Ever tried put e8400 back, but though the temperature doesn't rise so quickly, after system boot it also keep running at max power and then also goes to reboot after 2-3 min.

 

Then I decided to clean install MacOS on another drive to test clean installation. Done, and while I started from USB it was all predictable and good enough as usual. But as soon I installed default essential Sierra options which are:

Bootloaders -> Clover v2.4k r4173 UEFI Boot Mode

Drivers -> Misc -> FakeSMC

Customize -> System Definition -> iMac -> iMac14,2

and reboot, the NEW CLEAN INSTALLED system also began running at full CPU, and goes to reboot after a while.

Then tried again start system from the USB Stick but same result. It looks like something with system definition or clover settings incompatible and can't manage Q9650, but I still have no idea yet.

On other previous (my common working SSD) installation once tried to install new system definitions as Mac 3.1  (as Intel Core 2 Quad Q9650) doesn't meet iMac14.2 but in that case the system doesn't boot at all.

Also checked the system with HDD with WIN10 and Linux 22.04 and in both cases CPU and it's power management works ok as intended. Temperature OK, no rise, no issues.

Extremely need to make that machine alive, as there're a lot of projects that were done several years before so that are compatible only with that OS configurations i.e. LogicX + customized plugins set and also a few FCPX Projects.

Any suggestion please ? 

Edited October 2 by petals