I can't find the thread at R3D, but I do recall a few people fixed the flickering problem by changing around their power leads. It seems some people get the flickering if the lead connected to the 4-prong on the card was also supplying power to a fan off the same lead. (Y'know how each lead has a couple of 2-4 4-prongs coming off the power supply? Make sure the lead connected to your viddy card ain't also connected to a fan.

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