Your system was designed to work with a 75w GPU (such as AMD Radeon R9 360).  It should work fine with a 55w RX 550.  If you could, get a Dell version of a 4gb RX 550, so you won't have any issue with secure boot.  Otherwise, some retail and non-Dell cards may required to disable secure boot for system to recognize, else it won't boot.
Hello, I currently have a i5-7400, 24GB of Ram and a 256GB SDD.I am looking to upgrade to a dedicated GPU without upgrading the PSU and I want to keep it under $100, I was look at an RX 550x from HP but was wondering if it would work with my current 240W PSU.
Inspiron 3668 GPU Upgrade