Well if it has 2 sockets on the card, you probably need both you can get a splitter from your pc store that will give you more of those outlets
But I hear you on the size thing a friend of mine has the 4870 x 2 - the graphics card came in a box the size of a pizza box and takes up 3 slots to fit, its like something out of a space ship, also when its running the case temp rises like 15 degrees (c)
But the performance is awesome, yesterday he added a solid state drive, OMG, he now bechmarks 3 times higher!!!
Evil I say , I WANT ONE, now where a bank and my ski mask