Heyya =)
I think vFSB or 'FSB Overvoltage' is the voltage for the FSB itself, seperate from the MCH north bridge voltage. If I increase the 'FSB Overvoltage' by +0.25v, I can run my E8400 @ 475 MHz x 8(3800MHz CPU, 1900MHz FSB), 'Performance Enhance' @ Turbo(tRD = 7), DDR2 @ 1140Mhz(5:6 RATIO).
That's how I'm getting such good memory bandwidth out of an E8400 and decent DDR2 1066. I don't even use the '(G)MCH Overvoltage' setting as it always made my system unstable unless I left it at auto. I'm also running an ASUS 8800 ULTRA(G80, 128 SHADERS, 768MB) and it's overclocked to the max too. On top of that, throw in 3 500GB WD Platters @ RAID '0', with SATA II, NCQ, 16MB Cache and that's a lot of data moving through the X38 & ICH9R, at the same time.
I find that having a 3 x 500GB RAID '0' setup definitely reduces disk loading times for games and deathmatch servers, etc and also multi tasking is improved because there's less wait time during simultaneous disk reads across multiple applications that are running.