Hello. I have a computer with an RX480 8GB (reference card, got it on release).
At first I was using it on an old TV by HDMI. The screen being "zoomed", I needed to use scaling (HDMI Scaling on Display Option) option on Radeon Setting to get full screen on tv, and use custom resolution to get 60Hz (or else it was automatically set on 50Hz).
Since January, I bought a monitor to replace the tv (1080p, 60Hz and Freesync). Worked perfectly, no need to do any configuration.
Now I bought a hdmi/DisplayPort cable to connect the TV as a dual screen to use to browse internet or discord while playing game on the main screen. The issue I have is that when I use HDMI Scaling option for TV screen, I get a HUGE fps drop on the main screen, without being in any program (just drag and drop windows get me a drop). Plus, I can't set Custom Resolution with the latest driver for the TV (I was setting it with advanced setting before, and now it's gone from there and it's on Radeon Setting, but it give me error now).
How can I resolve these issue ?
My computer :
-RX480 8GB reference card
Also, I already uninstalled graphics driver completely (with a third party software, GURU3D Display Driver Uninstaller) ,and install the newest driver.
Thanks in advance ! And sorry for my bad english. If you need any other information, I'll provide it