Which 2(out of 3) pcie slots run at 8x electrical?

first two run at 8x and the third one runs at 4x. if you use one card then the first one runs at 16x and go to tigerdirect.com they have it for 199$ or zipzoomfly for 219 with shipping
 
by first two you mean 2 on the left right? anyways do you think I could fit a sound card and a NIC card in between and on the side of them?
 
so in order to use my ram in dual channel mode i'll have to put one stick in the blue slot and one in the black of the same area right? or do I have to put 1 in blue and 1 in black?
 
no you need to fill both blue slots first. for example 1 gb stick in one blue slot and and another 1 gb stick in the other one.
 
slot thats between the 2 pci slots is 4x rest of the two will work as 8x in crossfire. and you will only be able to use one pci slot of you use crossfire