Current setup:

AMD 4050e 2.1GHz dual core CPU
Onboard video: GeForce 7050
Tuner is HD Homerun, the old dual tuner model.
Mythbuntu 12.04 64 bit.

Those are the pertinent details. Reasons for wanting to upgrade:

1. The cpu simply isn't fast enough to transcode video to flash for use in mythweb in realtime.
2. PIP and PBP are really not very useful. I get video stuttering in the PIP window, and choppy video and audio in PBP.
3. I'm using the system for viewing / recording live OTA TV and watching video files. Currently, I have a 720p TV but want to upgrade to a 1080p model. Playing 1080p video is choppy on my current system.

I can choose to simply add a discrete video card (thinking a GT610 fanless low profile card). I think that will solve the issues with 1080p playback as the card supports VDPAU.

Without upgrading my motherboard (ASRock N68PV-GS), what's the lowest power CPU that would give me realtime encoding for video playback in mythweb?

Thanks for any insight.