I currently have a X6 1055T and do a lot of encoding with HandBrake (from ISO to H264 for example)
What would be a faster CPU in that domain if I were to replace my current one?
What motherboard are you using currently, if its not FX compatible then pick up these parts.
AMD CPU FX Series 8120 Black Edition 8 Core Processor Bulldozer
Asus M5A99X EVO, AMD 990X, S AM3+, DDR3, SATA III - 6Gb/s, RAID SATA, PCIe 2.0 (x16), ATX
Coolermaster Hyper 212 EVO, 4 Heat Pipes Direct Contact, with 120mm Quiet Fan LGA775/1155/1156/1366/AM2/AM2+/AM3/FM1
You will then be able to easily OC your FX to 4.0ghz and at this speed you will see one hell of a jump in your encoding work.