How does pci-e 16x work with 1 card?

hey guys, here is a detailed picture of my motherboard
http://www.gigabyte.com/fileupload [...] 0/4853.jpg

I am a little confused as it stated on this schematic that all slots are 16 x pcie 2.0. Am I to understand that the slots will only start running at
16
16
8
8
etc

when more than one card is installed? and until that point all slots act as 16x?

Its just I am contemplating moving my card from near the top, to the closer to the bottom of my case as I feel that heat from cpu and gpu are contributing to each others total temps.
Does this make sense or am I looking at it the wrong way?

heres my specs
gigabyte ga-990fxa-ud7
bulldozer fx running at 4.1ghz on zaalman 9700 heatsink
sapphire 6970
Will moving the card make a noticeable difference to the temperatures?
Thanks everybody
As a side note, I intend to either upgrade to 7970 very soon or go for a second 6970

(Note 3) For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16_1 slot; if you are installing two PCI Express graphics cards, it is recommended that you install them in the PCIEX16_1 and PCIEX16_2 slots.

(Note 4) The PCIEX8_1 slot shares bandwidth with the PCIEX16_1 slot and the PCIEX8_2 slot with PCIEX16_2. The PCIEX16_1/PCIEX16_2 slot will operate at up to x8 mode when the PCIEX8_1/PCIEX8_2 is populated.
This is from your motherboard manual.

Ah, Thanks man, I didnt even see that!
cheers guys