This voltmod applies to all HD 4870 series cards using PCB #B50731-10.
Performing these voltmods will void any and all warranties your video card may have.
You - and only you - are responsible for any damage caused indirectly (or directly) by these modifications.
GPU Voltage Mod (soldering)
A pencil VDDC mod is not available at this time.
Memory Voltage Mod (soldering)
Memory Voltage Mod (pencil)