The requirements to make 1080p video calls with Skype and your C920 are:
- Skype client that supports both C920 and 1080p calls (This is currently available on the Skype website under 5.7 Beta Client for Windows.)
- Bandwidth of at least 2.0 Mbps for uploading and downloading
- Core 2 Duo 2.4 Ghz processor
NOTE: If you have a lot of applications running on your system, it's possible that even with the recommended processor, you may not be able to get a 1080p resolution.