I don't think this is a driver problem. If you already have drivers for another AMD card, the 6870 should at least do a basic display. Even with no video drivers at all, Windows will run a generic driver to get you basic display. Are you using a VGA to DVI adapter. If so, be sure to plug it into the topmost DVI port, to cut costs most manufacturers only have on DVI port output an analog signal. If that is not the case, try plugging your monitor cable into an alternate port (if available). Failing that, you probably have a bad card, though it is strange that it passes POST but won't display, could be one or more of the output ports is bad.