Right.. well this is mostly copy/pasted from my entry on tomshardware because I keep thinking a dedicated forum would ever actually get responses.

I formatted my computer and put Windows 8.1 on. I previously had Windows 8. Windows 8.1 AND my Sony TV both think it is running at 1080p and it is NOT running at 1080p. Both Ubuntu and Windows 8 correctly reported the resolution as 1080p while it was actually running in 1080p, but 8.1 can't put it in 1080p yet thinks it is 1080p.

There was no hardware change, no cables moved around, nothing more than the re-install of the OS on my primary hard disk.

I have a secondary screen which is a 32" 1080p Sony Bravia TV. I understand that TVs are not intended as monitors however this was working flawlessly prior to the install. Not even the settings on the TV will have changed, only the OS.

I know what you're thinking, that if both the TV and the PC claims it's 1080p then surely it actually is. Well, it's not really: If I run any 1080p app it gets cut off the bottom and right sides of the screen and traverses onto the second monitor. Everything looks fuzzy from being lower res. If I make an explorer window nearly 1920x1080 so it reaches near the borders, then move it onto the TV it will not fit on the TV.

Relevant Specs:
Windows 8.1 x64
Sony Bravia TV - KDL-32CX520 Model # (Secondary)
Asus VX238 24" Monitor (Primary)
Gigabyte R9 280x 3GB Video Card

What I have tried & Notes:
- Changing resolutions
- Isolating the TV makes no difference.
- Switching which screen is primary/secondary no difference.
- Re-installing the latest Catalyst graphics drivers. Prior to reinstall I had the *same* ones which are definitely the latest as I had recently updated those days before formatting.
- Re-seating the graphics card
- I have a Playstation 4 hooked up on the other HDMI input and that definitely hits 1080p properly so there was no insane coincidence that occurred while I installed Windows 8.1