there are two things you can try, first, as I previously mentioned, you can load up CPU-Tweaker.exe or SPDTool.exe and gain access to changes not available in the bios, or, you can get a bit adventurous and try to load up OCZ's more relaxed 1066 SPD on your Gskills, I did this with some Adata stuffs I had, worked beautifully even though it was for OCZ stuffs, YMMV....
and, there are obvious problems with the 1066 if not running a phenom, the choice to run the 1066 isn't even an option....
and, to answer yer question one more time, the default settings and the range of setting changes available CHANGES when you toggle the ram (533,800,1066) in the bios.....if you want more options, I gave you some suggestions....
Trfc0): 75~327ns
(Trfc1): 75~327ns
(Trfc2): 75~327ns
(Trfc3): 75~327ns
set all these to 195 and give it a shot.....
there is a thread over @DFIclub forums, RE: mems and some explainations to your questions, linkee
http://csd.dficlub.org/forum/showthread.php?p=52184
read up, might help you a bit....found with a simple net search... (bank swizzle)
laterzzzzz...............