Most motherboards have an onboard video, unless you are gaming you should just use the onboard video card to browse/surf the web. You need to go to your BIOS and enable onboard video in your BIOS because when the motherboard detects a GPU, it automatically disables it.
Which motherboard do you have exactly?
If you don't have onboard video, then you can browse with one of the mining GPUs but you should disable them when you are browsing because you will run into crashes due to instability. Even surfing the web can cause the mining GPUs to easily crash. If using Claymore just hit "0" or "1" and it will disable the GPU.
I have the MSI B450. I have both connected, but my PCI-E cable was defective so I should get another one tomorrow. I am mining only RVN currently but might change to ETH with the 2070Super, but unlikely. Rather just keep it nice and easy. I will be setting this up once that cable come in.