A user, who is attempting to give a presentation via a projector in a conference...

The issue of video but no audio on a projector in a conference room can be resolved by utilizing an HDMI connection between the PC and the projector. HDMI supports both video and audio signals and is commonly used to connect a PC to a projector for presentations. Changing the input on the projector to VGA, changing the output on the PC to DVI, or modifying the projector's refresh rate will not resolve the issue. References: CompTIA A+ Certification Exam: Core 1 - Objective 2.5