I am a newbie, also having severel trouble downloading/syncing the blockchain. Mist Wallet 0.81 installed, got it working about half a year ago, but not now any.
I tried a complete download using geth 1.6.5, I got the entire chain downloaded including some error messages over the two and a half days period, but starting the mist wallet, it started a new download all over again...
Now - 7 days (!) later - mist is at 1,1 Mio of 3,8 Mio, created 21 GB (!) in my chain folder and my harddrive on c: has just about 4 GB left...
I am kind of frustrated - and thankful any advice: most urgent problem appears to be
1) How do I alter the chainfolder and references that folder in mist and geth?
2) How do I get it finally get the blockchain downloaded AND accepted by mist (any log files for examples which I need to shift from one folder to another? etc?)