It will work fine, don't be fooled by the myths. First thing is, even the FX5900 doesn't need AGP8x, and it's TWICE the card of that 4200. I think you'll see at most a 15% performance loss on that particular card by using it on an AGP2x board. In fact, the Ti4200 8x is just an ordinary Ti4200 with slightly faster RAM, it never needed 8x, they simply added 8x compatability to make people think it was "even better".
The cards are AGP 1.0/2.0/3.0 compliant, which translates into signal voltages of 3.3/1.5/0.8v, and transfer rates of 2x/4x/8x.
The card isn't low voltage. It's the same chip as used last year. I think they just add a resistor and a switch to drop the voltage when used on newer boards.
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