The following will guide you through the procedure of running a fast sync via geth --fast on Windows OS 10 for Mist for those running their Ethereum Wallet client for the first time.
Note:--fast can only be run if you are syncing your blockchain from scratch and only the first time you download the blockchain for security reasons, always ensure you are using the latest release; github.com/ethereum/mist/releases/.
Step 1: Open command prompt (Administrative privileges not required;Don't run as Administrator):
Step 2: Go the file directory for geth which looks like following on Windows OS: ~\Ethereum-Wallet-win64-0-7-4\resources\node\geth and drag using your mouse the geth file (a) from its location and place it into the command prompt window (b):
Step 3: You would see the following below if you did it properly: path to the geth file in your command prompt window
edit geth.exe to geth --fast as seen in (a) below.
Step 4:Click Enter and you should observe the following below if successful as the node begins to download the blockchain data;
Its progress above would be reflected in the Ethereum Mist Splash page progress bar as seen in picture below:
Step 5: Upon successful sync to the latest block, the Mist wallet interface should load perfectly.
Network Time error: if you see the following as shown in the picture below while geth is running:
Right click time (a) at the bottom right of the your screen as shown in picture below:
Select Adjust date/time and click Additional date, time & regional settings (a) in picture below located near the bottom right of your page.
Click set date and time(a) as shown in picture below:
Click Internet Time (a) and Change settings (b):
Click synchronize with internet server time(a), select time.windows.com as your server, click update(b) and press OK.(c)
This should fix the network time error and your would see geth client continue to download till the latest block.
What is really going on?
Instead of processing the entire blockchain one link at a time, and replay all transactions that ever happened in history, fast syncing downloads the transaction receipts along the blocks, and pulls an entire recent state database.