Some IO board info-
Slow fan: Might be a new fan that needs to run a bit. Also some board builders (myself included) offer the option of a 12 volt fan, which will run slower on the IO board (should still be somewhat fast tho). Some V6 boards have a jumper for 3.3v or 5v fan power, make sure that is set appropriately (silk-screened on the back of the board). 12v fans will need the 5v position, 5v fans should work in either.
Slow blinking lights... the power led (closest to the sd card slot) should be solid red, the other two will blink slowly back and forth at the menu screen. The digital audio led (by audio jack) should appear solid 'on' to the naked eye.
SOG: exact switch function depends on your board version, but generally, it selects whether the board adds the video synchronization signals to the green video signal (hence 'sync on green'), this was a common method on older CRT monitors "back in the day"