From what I understand 8 pin is only for a quad core chip.
Correct me if I'm wrong, but according to the MB manual, (I have the UD3P, same board 1 more PCIe slot), the 8 pin was only REQUIRED for Extreme Model CPU's. I have a q6600 using only a 4pin and I have no issues with a 3.4ghz overclock on it.
Well I used the 8 pin. Any everything turned out alright.
This question typically gets asked when the PSU only offers the 4-pin cable, which should be fine for processors up to 100W TDP (or even a bit higher). The 8-pin cable starts to be less optional around 130W TDP, but if you already have a PSU with the 8-pin cable, you might as well use it.
I was expecting a quantium leap in performance and I don't really see a whole lot of difference.
Nor will you by subjective impressions of OS performance. The X2 6000+ is plenty fast enough for running the OS and many applications. Not even a QX9770 would make basic computing tasks seem faster than a processor that is already fast enough for them. E8500 will be superior in some application types, but you're going to need objective benchmarks for the rest to "see" any difference.
Review sites are prone to exaggerating just how meaningful performance differences are to the user experience. They might make a big deal about an additional 20 fps but tend to gloss over that nobody is going to see any difference between 200 fps and 220 fps. Its like saying an airline passenger is going to notice the difference between 200 MPH and 220 MPH.