I installed Sparkle GeForce 8400GS 512 MB DDR3 PCI with Native HDMI Graphics Card with output to HDMI, DVI, and VGA to new Asus 24" LED monitor.
I have Dell Dimension 3000, Intel Pentium 4 CPU 2.8 GHz, RAM - 2.00 GB Dual-Channel DDR @ 199MHz.
Upgrated PSU - 400W.
Works just DVI connection (perfectly). VGA and HDMI have no signal. Any suggestions?
I only can think you did not selected the right input in the monitor;
Some monitors the SOURCE is different on each connection, you should change your display "input" to the one you are using...