Removing top panel is kinda up to you. With PCIe slot covers removed air generally flows front to back very well even if top is a vent. You could experiment with top on and of by running same heavy CPU & GPU load and see which cools bests. I don't like top venting because my cases often have things on top of them.
Assuming you have Asus X470 Aorus Pro (rev. 1.0) rev. 1.0 I looked at motherboard manual. It has 7 fan headers' 3 on top edge, 3 on right side/front just below main power socket and 1 about middle of bottom. With Smart Fan you can have it do an automatic fan curve setup or your own fan curves. I usually do the auto setup, then modify it as needed. Below is bottom part of page 33 in manual:
Smart Fan 5
Monitor
Allows you to select a target to monitor and to make further adjustment. (Default: CPU FAN)
Fan Speed Control
Allows you to determine whether to enable the fan speed control function and adjust the fan speed.
- Normal - Allows the fan to run at different speeds according to the temperature. You can adjust the fan speed with System Information Viewer based on your system requirements. (Default)
- Silent - Allows the fan to run at slow speeds.
- Manual - Allows you to control the fan speed in the curve graph.
- Full Speed - Allows the fan to run at full speeds.&
Fan Control Use Temperature
Allows you to select the reference temperature for fan speed control.
Temperature Interval
Allows you to select the temperature interval for fan speed change.
Fan/Pump Control Mode
- Auto - Lets the BIOS automatically detect the type of fan/pump installed and sets the optimal control mode. (Default)
- Voltage - Voltage mode is recommended for a 3-pin fan/pump.
- PWM - PWM mode is recomm