After much tweaking, I've finally managed to get my E6850 stable at 3.6ghz using just the stock cooler. Max temp loads never exceed 63C during prime95 torture.
Is it really worth it? Am I going to notice a difference opening photoshop? Manipulating images? Playing games? I almost never encode. VCore is at 1.4v and I wonder if that will significantly shorten my CPU lifespan, as well as my +0.1v FSB and PCI-E I had to do to get my system stable.
I doubt you'll notice much difference in opening programs, as drive speed comes into play. As far as manipulating images if your working at pro-sizes and resolutions, then you'll see a definate difference.
With games it depends on what game and what vidcard you're using. If you got a low-to-mid range vidcard, it'll probably bottleneck there if your playing a high-end game.
I wouldn't worry about 1.4V, as your CPU is spec'd to 1.5V - so you're still in it's designed limits.