That power supply that you linked to, although the 3.3V and 5V rails looked a little low to me to be rated a 500W PSU (my 480 Antec has much better amperages than that, and it's rated 20W lower...), but it looks like it'll have fairly good 12V amperage.
About the vcore mod, first things first - let's fix the problem you're having. Doing the vcore mod when your machine is crapping is only going to exacerbate the issue.
As for how to do it, four different variants are very, very well documented on OCW (pictures are included for the ignorant, like me
). It's heinously easy - I did variant one, which changes 1.075, 1.100, 1.125, and 1.150 to 1.475, 1.500, 1.525, and 1.550, respectively. Just a word of caution that the 1.075 setting the machine will not post the first boot, and then you'll see your voltage setting back on auto - the bios will kill this setting, since it's under minimum vcore rating for the chip. So your new usable settings would be 1.100 (1.500 actual), 1.125 (1.525 actual), and 1.150 (1.550 actual).