Just to share what I have done to my 5GH Jallies.
1) remove the side casing (not the top one with the logo) - because air are trapped inside
2) flip the fan to blow on the heatsink instead - because IMO, it's better to blow on the heat sink rather away
3) invert the whole jallies e.g. putting it upside down - because the bottom is also heated up when it's running, so I kept the bottom surface on top for better cooling
Next step is to flash those jallies to 7GH/s