20" Apple Cinema Display (ADC)

Hi everyone,

Powermac G4 Sawtooth

Specs: OS 10.4.11, 1GB ram, 80GB HDD, Dual 450mhz
Display Card Specs: ATY RAGE 128 Pro, 16 MB VRAM

Previously I was running a 17" Apple Studion Display LCD and I've recently purchased a 20" Apple Cinema Display LCD (both used ADC). When running the 17", nothing goes wrong, but when I plug in the 20" LCD and switched the powermac on, the screen loads the apple grey loading screen then the screen turns black. I thought i may have done something that could have damaged the port for the ADC, but when using the 17" once again, it's fine.

I've read a couple of post about this, but there hasn't been any clear answer to what could be wrong. Questions that I need some answers from to start with are:

1. Do i need to upgrade my gaaphics card to something stonger or better? (i.e nVidia Geforce 2 MX 32MB DDR AGP G4 VGA+ADC)

2. Is there something wrong with my display? (Heating eliment or fault in something internal)

3. This mac came from someone using a G5 powermac. Would i need to get a Graphics Card similar to that? And if so, could it fit into the G4?

Please help me! Cookies for any who solves this =D (Virtual Cookies)