I bought ATI 5870 and did complete install yesterday whilst I had the computer connected my hdtv via DVI-HDMI cable and everything is working fine.
Connecting regular DVI cable to my monitor even when the monitor is powered off causes the screen go blank on the second display connected via...
It's quite weird when everyone is complaining about the temps/noise as neither seems to be issue according to some tests:
Noise: http://www.guru3d.com/article/geforce-gtx-470-480-review/13
Temps...
I will need some serious convincing to swap from Nvidia, so I'll go with GTX480 and try to get my hands on some cheap 5000 series so I can try it out and see how excellent it is myself.