Flickering is normal if it takes place in the order of 5 tenths of a percent. If you have bigger flickering, then try this:
Do not connect the USB pedal cable to the USB HUB. Connect the pedals to the USB connector on the motherboard.
Pedals are grounded via Leo Bodnar unit and then via USB to PC. Flickering problems are sometimes caused by Direct Drive steering wheel connected to the same socket as PC.  Try to connect PC to the different socket than Direct Drive steering wheel.
If flickering still persists, it is possible that you have poor grounding on the house wiring. We recommend you try to connect the pedals to a notebook that runs only on battery power. This will determine if flickering is not originating in the electrical network.
If flickering disappear on the notebook that runs on battery, than you need to ground pedals to you rig. Check photos of grounding from our customers.