Overclock HD4870 X2

Is it possible to raise the frequency GPU on this card to the maximum? what interests me is first of all flasher the BIOS to increase the voltage V-GPU after the possibility of increasing frequency over GPU 850MHz or even 880 MHz. Is that all that is feasible a HD4870 X2?

I have a 8800 GT 512MB, I have a flash bios with Nebitor and I increased the voltage thereafter at 1.1 volts is my permit it to increase the frequency of 600MHz to 756MHZ stable, 14040 3DMark06 points. So that's exactly what I want to know if this is feasible with an HD 4870 X2?

yes it is feasible but probably with an adequate cooling (WC)

If feasible can you help me get a solid confirmation, so I can see the dark HD4870 X2.

956 million transistors on 55nm fabrication process, PCI Express 2.0 x16 bus interface , 256-bit GDDR3/GDDR5 memory interface, Microsoft DirectX 10.1 support, Unified Superscalar Shader Architecture these are some Features of HD 4800 Series