Please post specific information such as CPU, Motherboard, The OC speed and Vcore of your CPU, Memory (Timings and DRAM Core).
If you can provide links to the exact model on either the official website or newegg that would be helpful to the community so that we may better assist you.
EDIT: Also please go to Start > msconfig > startup
See if there are a bunch of applications starting when you start the system, might not have anything to do with the overclock if you recently installed a few things. Some/A lot of apps automatically start when windows is loaded which slows start speed.
Sometimes through the boot and rebooting to get to your stable overclock the graphics drivers can get corrupted, not enough to crash the machine but enough to affect the bootup, try uninstalling and then reinstalling your graphics drivers and see if that changes anything.