I have an original mac pro 1,1. I had been running two monitors off a HD 4870 (apple version) no problem. A 1680x1050 samsung and a 1280x1024 samsung. I still had the GeForce 7300GT in the machine but it wasn't connected to anything. I recently bought one of these 1080p TV/monitor combos (1920x1080) and connected it to the GeForce 7300GT via DVI. I'm not using it as a primary monitor - just for a TV in another part of the room and over a keyboard I have set up for Garageband piano lessons. Then things went south. The larger samsung monitor on the HD 4870 started flickering to black sporadically. Sometimes more than 10x during a minute. Other times just randomly once in a while. I took the 1080p TV/monitor off the GeForce 7300GT and put it and the larger samsung monitor on the HD 4870 - i.e, the two biggest monitors on the best card. I put just the smaller samsung (1280x1024) on the GeForce 7300GT. Still having the problem. I tried resetting the PRAM - doesn't seem to do anything although I'm not positive I'm doing it right. Any ideas? Is this machine too old to push that many pixels? The HD 4870 is not supported on this machine - maybe there's a reason? Anyways, at this point not sure what to do except maybe spring for the 27 cinema display I dream of and just run that and the 1080p TV/monitor off the HD 4870 and simply remove the 7300GT. Don't really have a thousand bucks right now though.