I just ordered the new 9800 gx2 and i have a Asus p5e x38 chipset.. I was wondering what are my "benefits" (so to speak) in havening my chipset support PCI-E 16x 2.0??? Alot of mobos only have the pci-e x16 not the 2.0.. but it would still work on a mobo that does NOT support PCI-E 16x 2.0!!!!
[Tabs through the book of things you should know before buying a $$$$$$ video card]
Ah, here it is....PCIe 2.0.
What you need to know is that PCIe 2.0 doubles the bandwidth of each lane from 250 MB/s to 500 MB/s. So you multiply that by the number of lanes to get your bandwidth. In your case, we are talking about 16 lanes. So the 250 MB/s multiplied by 16 (x16 notation) yields 4GB/s bandwidth for PCIe 1.1. For PCIe 2.0, you get 8GB/s bandwidth with 16 lanes. The problem is that video cards aren't needing bandwidth beyond what PCIe 1.1 offers so it doesn't do much on that side of the fence at the moment.
Second off, the power supplied to the graphics card through the PCI slot is doubled as well. PCIe 1.1 gives up 75W where PCIe 2.0 will do 150W to the card. So if a video card ever comes out that needs less than 150W you won't have to have a power adapter for it. Yours does not fall in that category.
Since you are using the same 16 lane size, PCIe 2.0 video cards don't have a physical size difference than 1.1 cards (see below)
I like to think of it as USB 2.0. You can have a USB 2.0 device and still use it in a USB 1.0 port. The catch22 is that its running at USB 1.0 speeds. The good news for those with PCIe 1.1 slots, PCIe 2.0 video cards aren't up to speed yet....get it? Up to speed?