I have a PC with a Radeon HD 3870 (Sapphire) graphics card and a new Toshiba 40RV525U HDTV. I'm trying to setup the PC to clone video output to the HDTV via DVI->HDMI. My primary monitor is an HP LCD that's been working fine forever.
The setup works, in general. I've got the grey DVI->HDMI dongle that came with the Sapphire, Catalyst detects the Toshiba monitor just fine and all its supported modes, and initially my cloned PC output displays and looks fine.
The problem is that the HDTV will randomly lose the signal and go to black, then flash the "No input signal" box that I would see if I selected an unattached HDMI input channel. This usually happens within 30s to 60s. If I change the input to something else and then back to that HDMI input, it usually displays the cloned output fine again. At first I thought maybe it was some sort of power-down/screensaver thing since it seems to do it faster if I leave the computer idle and no display changes are happening, but at this point it seems relatively random.
Has anyone else run into this, or have any suggestions on how to fix it? Between this and the 40RV525U not getting audio over HDMI from my XBox 360, I'm starting to think maybe I should take it back and pick up a different TV.