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I decided to post this here, so at least there's a guide for other people on how to fix this issue. I've looked for a solution, but never found any. Luckily I solved it by accident.

The issue (100% reproducible):

  1. On Windows 7 64-bit with Radeon HD 4870 and Catalyst 12.3 (and all other Catalysts I've tried)
  2. Connect a HDMI cable from the video card dongle to TV HDMI in (Samsung Full HD LED, but I believe the TV doesn't matter)
  3. Use "Extend Desktop" in Catalyst Control Center on 1920x1080 resolution
  4. Change source on TV to HDMI, so that you see the extended desktop on the TV (the picture comes out OK in my case)
  5. Wait 30 seconds
  6. The TV screen will automatically turn black and then say "No signal"

Also, there is no dialog about things like "Are these settings ok? Reverting back in 30 seconds if no answer" or anything like that

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The solution which works for me, at least:

  1. After extending the 1920 x 1080 desktop, set the resolution to for example 1280 x 800
  2. Wait for 30 seconds
  3. The screen will now "revert" on its own, as per the issue, but it will now revert to the 1920 x 1080 resolution instead of No Signal/black screen

I have no idea why that happens, as there are no dialog screens appearing at any point. But at least this works in bypassing the issue. What I believe is happening, is that there should be a dialog screen asking for the user to accept the active settings, but for some reason it is not displaying, and it reverts back to the previous settings (not original!).

If you have more info, please post!

Hopefully this will help someone with the same issue, though...

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