i7-3770 300 pass 11h - 
Probably wrong render setup. Maybe those windows blinds, or lots of reflective materials. Are you using portals?
Have you seen these?
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516731
https://coronarenderer.freshdesk.com/support/solutions/articles/5000501660
https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983