Integrated GPU apparently bad; added GPU card; still no signal to monitor

No signal to monitor
Checked cable; tried various cables
Been thinking about replacing old monitor, bought a new one (Dell P2219H)
Still no signal; deduced integrated GPU was bad
Purchased SAPPHIRE pulse RADEON RX580 & power cable
Installed card; connected to power supply (REVOLUTION Xt) 12 pin to 8 pin at card
No signal at monitor, so impossible to install drivers

Appreciate any help.
Thanks,
Pat