I want to hook up 3 monitors to my computer at work. I bought an adapter from amazon that converts HDMI to mini Displayport and it seemed to work. I was able to have all 3 monitors on at one time, however, my 3rd monitor is a tv and when you connect to a TV, it cuts the edges off. For the life of me, I couldn't find where to scale the "mini Displayport", only the HDMI. So I tried to switch and plug my monitor in through the adapter, and the TV directly into the HDMI. My monitor would not show up through the adapter. After switching the adapter from monitor to TV a few times, it seemed to fail. I am sending that adapter back to amazon, and I bought a new adapter from best buy. This adapter works with either the TV or the monitor, but now my graphics card is only allowing me to use 2 screens at a time. It will let me use any combination of 2 (of the 3) screens, but limits it to 2. I believe this adapter is working fine.
I also updated my radeon version to the most recent yesterday when the adapter started acting weird. Today, I was trying to downgrade back to the version of radeon I had yesterday, to see if maybe that version would permit the 3 screens, where as there might be a glitch with the newer version. As it turns out, it doesn't matter what I try, the radeon installer always adds the newest version (I was trying to download 17, but it automatically goes to 18.) Below are the specs for my graphics card and the adapters.
Graphics Card: AMD Radeon HD 7870 GHz
Amazon adapter (returned): Cable Matters Active Mini DisplayPort to HDMI Adapter (Active Mini DP to HDMI) Supporting Eyefinity Technology & 4K Resolution