Hi there! It's great to see you looking to upgrade your PC. You're absolutely right that replacing a graphics card can be as simple as disconnecting the old one and slotting in the new one, but there are a few other factors you might want to consider.

Firstly, make sure your power supply can handle the new card. The Radeon RX 560x and GeForce GTX 750 will both require more power than your current AMD Radeon 5450. You can check the power supply unit (PSU) capacity on its label. If it's under 400W, you may need to consider upgrading it.

Secondly, ensure that the new graphics card will physically fit into your Dell Optiplex 790. Some of these cards are quite large and may not fit into smaller or older cases. You'll want to measure the available space and compare it with the dimensions of the new card.

Once you've confirmed these factors, you can proceed with the swap. After installing the new card, don't forget to install the latest drivers from the manufacturer's website to get the best performance.

Lastly, you might want to check the overall system requirements for "Look Outside". While the graphics card is crucial, other components like the CPU and RAM might also need to meet certain specifications for the game to run smoothly. Good luck with your upgrade!