I bought a XFX Double D FX-787A-CDFC Radeon HD 7870 and set it up using the HDMI, DVI and Mini DisplayPort (using an Apple mDP-to-VGA adapter). I hooked it up, installed the drivers and rebooted. The image came up on the third monitor in a weird resolution. Why did this happen and how can I fix it? I am using Windows 7 Ultimate and the system is completely updated.

Side note: When I disconnect the Mini DisplayPort adapter it works fine, however for my work I need 3-4 monitors.

  • Did you try changing your screen resolution within the AMD/ATI program and not just Windows? – Kruug Apr 5 '13 at 20:16
  • Did you try changing the resolution on the monitor with the weird resolution? Silly question but you didn't indicate if you even tried it. Furthermore what is the wierd resolution exactly? – Ramhound Apr 5 '13 at 20:31
  • @Ramhound The Rez Was 800X600 And I Did Adpent To Change IT With No Luck – iPat8 Apr 6 '13 at 5:02

I'm not sure if this will help, but the Eyefinity how-to page indicates that your first two monitors can connect with any display output (HDMI and DVI, in this case), and your third monitor must be connected via the DisplayPort.

Now, you say that the third monitor (presumably the one hooked up via the mini displayport to vga connector) came up in a weird resolution. You don't mention what resolution this is, though. Apple limits the maximum resolution to 1920 x 1200. I'm guessing that's at 60Hz, too. If you are trying to go higher than 1920 x 1200 at 60 Hz, or higher than 1600 x 1200 at 85Hz, you may want to lower the resolution or refresh rate.

  • No The Rez That I Wanted Was Retively Low and The Resfress Rate Suported By The Monotor Is 60 Hz no Higher – iPat8 Apr 6 '13 at 5:04

You need to use an active display port adapter. I can't tell if the Apple one is or not but I would guess since you are having problems it is not. I have a 6950 with my main monitor using HDMI one side monitor using DVI-D and the other using this adapter to DVI. It works very nice the only downside being that occasionally when I wake the computer from sleep the monitor on the adapter doesn't wake up. If I unplug and replug the adapter it works.

AMD has a recommended list of adapters here. The Apple one is not on there but there other VGA ones on there you may want to check out. Additionally you could reconfigure the setup so that the DP drives the HDMI or DVI monitor and run VGA off of the DVI output.

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