Hi there, I have recently added a dual 1.25 ghz Power Mac G4 MDD to my collection. It has 2gb of RAM and I dual boot it with Leopard and Tiger. I decided to replace the original ATI Radeon 9000 Pro graphics card for an NVidia GeForce4 TI4600. Whilst the MDD worked fine for a few days, it now refuses to boot when the new card is used. When I turn the Mac on there is no sign of life at all - no lights, no fans, no chimes etc. However, when I put the old graphics card back it boots, and operates, without issue. To troubleshoot this I have removed the PRAM battery for 15 minutes and then reinserted it without success. I have also tried resetting the PMU to no avail. Moreover, I have also left the new card in the MDD, with it plugged into the mains, for a few hours. Strangely the computer turns on without me pressing anything, where a loud beep is audible before it abruptly cuts out. This has happened on several occasions. Does anyone have any idea what this could be? My initial thoughts were that the power supply unit could be faulty; however the fact that the old graphics card is working makes me doubt this. Any help would be gratefully received. Thanks.