GTX 260 PCI Express x8??? WHY???

Hi guys,
i just build my first pc...
my motherboard has 2 PCI -E slots.....on top of one of them it says in big bold letter PCI EXPRESS X16
I installed my GTX 260 in there......
when i turn on my computer and go to Nvidia Control Panel....on bottom left corner therer is link that says "System Information" ....when I click on it. it shows all the info of the card and all the way at the bottom it says "BUS: PCI Express x8" .....WHY IS THAT???? shouldn't it say ".....x16?"
i tried installin my card in both slots and it says same thing in both of them.......
my motherboard came with "switch card"....i dont knw what that is but someone told me that by installing it in the 2nd PCI-E slot, I will get all 16x speed on my card or sumthing....i tried that too....but when i put in that card....my computer turns on but not the monitor.....i tried this with 2 diff. monitors....

Plz help me guys.....(1) how do i get x16 speed?
(2) what is this switch card?

thank you guys....