ODD fan is responsible for cooling down GPU. There was a temp sensor connected to the optical drive. You must have forgotten to connect it back to the SSD.
Hi and t hank you for the testing! Looks like it's the first mac model in more than 10 years when Apple changed SMC (https://en.wikipedia.org/wiki/System_Management_Controller) specs. They use new 'flt' type for smc key where the known 'fp78' was expected. I couldn't fine anything related to this ...