What is the make/model of your motherboard?
The motherboard web site will have a list of supported processors as well as the requisite driver level to run.
Look at the bios info, it will have the current bios level.
You might be advised to reinstall the old/working 8600 to do the bios update.
A failed bios update can be nasty to recover from.
I would always flash a bios from usb, not the internet.
A internet or windows problem could cause the flash to fail.
When updating a bios, read the instructions carefully.
Be patient and do not interrupt the process.
It will appear that nothing is going on for perhaps 10 minutes.
Successful booting in safe mode suggests a driver problem.
Safe mode boots with only essential generic drivers.
You could try downloading and installing the latest chipset drivers for your motherboard.