ok heres the deal, there is no such thing as a 'PCI-E Gen 2.0 bug' only the 'dont know how to enable Pci-e Gen 2.0'
and the lack of understanding as to how the standard works
this first raised its head on the early Abit boards, even though it was enabled in bios, it still would not 'switch'
switch being the apt word here, it can be tricky if you have already had a gen 1 card in there, as it will default to gen 1.
it is quite simple in the general description of how to do it, enable in bios Gen 2 mode, then shut down computer, and unplug it, leave 20seconds and then boot from cold.
this will allow the 'Switch' to take place
the tricky part is understanding in what order some settings need to take place in the bios before this cold boot. trial and error usually sort it. here is my ASUS board with no problems in Gen 2.0 mode.
http://img704.imageshack.us/img704/8950/28583212.jpg