well im not searching on the net all day for articles about it, i cant be bothered plus ive got the builders in here, but from a personal note, i built a pc for someone, he had a ati 9200 card built by saphire, and a m-audio 24/96 card, now i put these side by side, never even thinking there would be an issue, but we kept getting pops, clicks and crackles, the first thing i tried was new drivers, still the same, so my mate said, try moving the cards away from each other, so i moved the sound card to the furthest away slot, and hey presto, the interferance stopped.#

I then later bought a terratec dmx6/fire for myself, and in their manual it says not to put the soundcard next to the graphics card