You can set bclk to which ever you like. It should be 100.00 but if you want it to read 100.00 in windows set it to 100.03 in bios.
What 4 boxes on the welcome screen seem to stop suddenly? If your boot drive is SSD then all you should see doing boot up is the gigabyte boot screen then you should see the 4 colored balls appear forming the windows logo but they might not complete the whole logo then you should see the welcome screen maybe a logon screen and/or your desktop.
A0 is for A O.K j/k i dont know what it stands for but yeah thats normal.