Ensure you are using the correct 19-pin cable. If your case uses older USB 2.0 connectors (usually 9-pin), they will not fit into these 3.0/3.2 headers without an adapter.
If you're ever unsure about a specific motherboard's layout, it's always best to check the digital manual on the Official Manufacturer Support Page or ASUS Support to confirm the exact specs for your specific model. usb e12 vs usb e34
However, some builders prefer using first out of a sense of "logical order". You would only strictly need both if your computer case has four or more front-panel USB 3.0 ports, requiring two separate cables to be plugged into the motherboard. Key Takeaways for Your Build Ensure you are using the correct 19-pin cable