New to Drop bar Road Bike, severe upper back/neck pains
You should try a professional bike fit. 

Just because you are 179 cm doesn't mean a 56 is right for you (the sizing of a bike with a given number varies on the type of bike and manufacturer and model). Normally, when you switch to drop bars, you will be sore (but pain is different, and should be alarming, though going for a 40 minute ride while just starting out may be a bit much). The geometry of the bike can also cause problems - racers may cause more pain than touring bikes due to their more aggressive geometry, for example. 

Here are some tips from sheldon brown on pain, and what to do about it.