After installing BT5R3 GNOME 64 on my PC, I was met with a no screen error upon starting the xserver, even though it ran (in low resolution) during installation via USB. I used the following guide to install the drivers: (Including the outdated version of the driver: 11.6)
That got me back the the quality I was seeing on the USB boot. I then went on the AMD website and installed the driver with the name:
Upon a reboot of my system, The xserver failed to start with a black screen.
Going back and re-installing the DEBs mentioned in the guide and starting the xserver again, I got what looks like a 1080p (That's the resolution of my monitors) resolution, but is actually scaled down so I can't quite tell. By "scaled", I mean that there is a large border around all four edges of my screen. This is similar to what I have seen when installing the card in windows, corrected by using the "Over-Scan" feature of the windows version of AMD Catalyst. My graphics card also seems to be under-performing as window dragging is very laggy and I am unable to turn on "Visual Effects" from the "Appearance" menu. This, I assume, means that my graphics card is not installed properly, and probably has something to do with me using the outdated version of the drivers. Could somebody please tell me how to fix the scaling and performance issue? Thanks for any help I receive.

Graphics card: PowerColor AMD HD Radeon 6870
8GB RAM, 6-core CPU at 3.6 ghz,One monitor is using HDMI, and the other is using DVI.