If you want to vent out through the roof, make sure that there's an opening (air intake) at the lower level of your garage.
GPUs aren't noisy at all (except from Low Quality Heatsink Fans of substandard/old GPUs)

You need a proper airflow:

• Hot Air (Light) - Venting out to the top area
• Cool Air (Heavy) - Intake from the lower area, not necessarily need fans
• Mining Rigs - as low as possible

You don't have to click "Share" images on IMGUR in order to link them here.
I did that once and I got much, much weirder comments from the users.