Display problem Mac Mini G4 10.5.7

Have you looked it up on the ASUS site?
https://www.asus.com/support/FAQ/1015526/

Can you change the signal format in the display settiings? 1080p is the native one on your monitor, try difrent ones if availabe. also test difrent resolutions.

If you want to use a TV as a secondary or mirrored monitor. All you would need is a Mini-DVI to HDMI adapter. Use the adapter to connect an HDMI cable between your computer and the TV. Once connected you will have an option to use it as a secondary or mirrored (exact copy of what is on your laptop) monitor. If you have one of the newer macbook pros you need a Mini Display port to HDMI adapter.

Check your settings,both bios and display,for the display priority.Either the settings has been set to inbuilt display and thus cant display on external monitors or the external monitors have been disconnected in bios settings

Try to connect your Mac Mini to another DVI-capable monitor. May be your DVI out on Mini doesn't function at all

When your notebook computer is connected to an HDMI device, you may encounter certain display and sound issues. For example, if you have your notebook computer connected to an LCD TV and/or surround sound speakers with a high-definition multimedia interface (HDMI) cable as part of a home theater system, you may encounter some common HDMI display and/or sound issues such as the following: If you are experiencing one of the following issues, click the link to go directly to a section of this document for a resolution. If you are experiencing an HDMI display or sound issue that is not listed above, please contact HP for assistance.

• Content protected error message
• images do not display properly
• Surround sound option is unavailable

Set HDMI sound output Make sure that HDMI device is enabled and selected. To make it the default sound playback device, select ATI HDMI Output and then select Properties . The HDMI cable must be connected when it is configured. Use correct HDMI cable for your HDMI device There are three types of HDMI: 19-pin (normal head), 19-pin (small head), and 29-pin. If your computer and HDMI device use different cable types, adapters are available. For more information, see HP Notebook PCs - Overview of HDMI and DVI Connections for PCs . Content protected error message If you are playing an HD DVD on your notebook computer while it is connected to an LCD TV with an HDMI cable, you may see an error message that reads, The content is protected. The content is not allowed to be played in current mode. This error sometimes occurs when single mode settings are selected. To resolve the issue, click to accept the message when prompted, and the movie will play. images do not display properly When the notebook computer is in HDMI mode, images sometimes are distorted or do not display at all. To resolve this issue, use the HP Support Assistant to test your computer and install any updated drivers. Alternately, download and install the latest NVIDIA GeForce driver from your model from the HP Software & Driver downloads page . For more information about downloading and installing drivers for your HP notebook computer, please see the Locating HP Software, Drivers, and BIOS Updates in Vista support document. Surround sound option is unavailable First, confirm that your notebook recognizes HDMI audio by right-clicking the Volume icon in the Windows system tray and selecting Playback Devices . If you do not see HDMI Output then you may need to reinstall or update your audio drivers. Also, make sure your notebook's BIOS is up-to-date. When using WinDVD to play a movie after selecting HDMI as the default audio output, the surround sound option may be unavailable. To resolve this issue, please update to WinDVD version 9.0 or later at the HP Software & Driver downloads page . If you are using the MediaSmart program, make sure you are using the latest version. For more information about downloading and installing software updates for your HP notebook computer, please see the Locating HP Software, Drivers, and BIOS Updates in Vista support document.

The best option here is to use your TV as a secondary monitor for your iMac. Doing so would require the correct type of connector in your case a mini-DVI to HDMI connector.
Once it is connected, you have three options - you can have it mirror what's going on on your iMac's display, have it act as extra monitor 'real estate' - that is to say extra space that you can drag windows onto and so on - or you can have the TV act as your primary monitor.
All of these options can be changed when your TV is connected through Apple menu > System Preferences > Display > Arrangement.

You don't really need to worry about the DVD player on the TV as the Mac OS has a DVD player application built into it. You can use it or the TV's DVD player, it's really up to you.

As for connecting both of them to the same speaker system, you should be able to purchase a connector that will go from the audio out port of your TV to the audio in on the back of your iMac. You would then be able to select the TV's output in Apple menu > system preferences > sound > input.

Later MacBook (Pro) use a mini-DVI connector that does not pass analog needed for composite or S-video. Was yours ever working? And most DVI connectors do not pass sound as seen by your cabling. You cannot detect display through RCA. You just set it in Sys Prefs :: Displays, try some other settings, although your seem right.
I have a white early-2009 MacBook and mini-DVI to HDMI adapter (monoprice <$10) and HDMI cable and have not connected the TOS-link for sound, yet--just slideshows at 1920x1080. You will get a much better picture digitally. -Ken

his step-by-step guide describers how to obtain and install ViewSonic VA720 drivers for Mac.
1. Define your ViewSonic Monitor device model.

2. Define your operating system to install your ViewSonic Monitor device. Note: Update Drivers in Mac

3. Browse Monitor Drivers.

4. Find ViewSonic Monitor Drivers.

5. Select ViewSonic VA720.

6. Download ViewSonic VA720. Note: you can update all Drivers automatically with RadarSync (Freeware) or Driver Detective (Shareware).

7. Install ViewSonic VA720.

8. Restart or reboot your computer to finish your driver installation. Note: you can backup your computer drivers before updating.

Unplug both from power , and remove mac battery, restart first mac then TV, already connected.

Check source with tv remote, and ensure mac res is correct.