Have you made sure you didn't put too much or too little of thermal compound and on top of that did you make sure your heatsink is sitting correctly? Try a program like Motherboard Monitor 5 to see what kind of temp readings that gets and see if it corresponds with the BIOS temperatures. The only way to change your Vcore is in the BIOS although there are some windows based OC'ing software that I suppose might be able to change your voltage.
I don't understand why he's saying it's your Vcore simply because you have a VIA chipset board. I have both VIA and Nforce boards and it has the same vcore. Get CPU-Z and see what it reports your Vcore at although motherboard monitor 5 also reports it