Hi guys

I am considering testing out mining.  I have read a lot of mixed views. Many say you will never earn enough to pay for the power that is used. Some say differently.

I do not want to spend a thousand plus just to test and have some fun. So if I want to play and see, is there a guide for a raspberry setup running 5+ USB keys? 

What are the fastest USB keys for mining?

Any direction you can provide to get me started would be appreciated