Just looked at a PC that would hang on boot for a minute or more.
Found 2 problems:
The first was a furballed CPU heatsink:
The second which was the main reason was the solid state drive (SSD) where Windows was installed was dying and the writes to it had dropped to 12-24 MB a second where it should be 200+:
I cloned the SSD to a standard hard drive and got normal write speeds:
That proved the motherboard was OK and the SSD was at fault.
I advised the customer to replace the SSD with a VelociRaptor drive, giving improved reliability with comparably fast boot speeds.