Generically speaking, maximum size depends on the interface you're using, it doesn't matter what GPU you're using.
- VGA: There is no standard maximum resolution.
- DVI: It depends on the type, look at https://en.wikipedia.org/wiki/File:DVI_ ... _Types.svg for the connector you have
- Single Link: 1920x1200@60Hz
- Dual Link: Limit depends on implementation
- DVI-A: Same as VGA
- HDMI: Depends on HDMI interface (i.e., HDMI 1.1, 1.2, etc...)
- DisplayPort: Depends on DisplayPort interface
So only DVI Single Link has a hard limit. Everything else depends on the bandwidth, but nominally this tops out at 2560x1600. Newer standards will probably include 2K, 4K, and Ultra HD.