My Core Voltage In CoreTemp, What Does It Tell You?

Depends on the motherboard your using.
that is a very large drop in v-core for any motherboard.
you need to list your specs.
it could be anything from bad bios reporting to poor design or even your psu not keeping up with the current demand of the entire system.

Here, hope it helps.
Intel Core 2 Quad Q6600 OC'd 3.42Ghz.
XFX 780i Motherboard.
Kingston HyperX RAM 1066Mhz.
Zotac GTX260 216 Edition.
Corsair 450W VX Power Supply.
Western Digital Blue 320GB Hard Drive.
Antec 900 Gamers Case.
Arctic Cooling Freezer Pro 7.
DVD/R Drive.
6 case fans

I didn't get an email notification so sorry for the late response
Even though Corsair makes great power supplies your way under powered .
The GTX 260 min requirements are 500 watts and 36 amps on the +12 volt rail
Your shy 50 watts and about 4 amps just with the GPU by itself.
You cant skimp on the power supply.
I would start there

Yeah, i realise that now thanks. Can i ask your opinion on which to get, im looking at 750w corsair or 850w OCZ gamextreme

If you can afford it the 750HX is one of the best I can think of off the top of my head and it has a 20.00 rebate  
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I live in the UK so i cant actualy find it that cheap. But ill keep looking, thanks. How does that differ with the TX, do you know?

The difference between the HX and TX are night and day for the overclocker but not that big of a deal on a budget system.
They’re both very good
The TX has about 60 amps available on the 12 volt rail, a little over 81% efficiency at full load and 720 max watts available on the 12 volt rail
The HX has 62 amps on the 12 volt rail, about 86% efficiency at full load with 744 watts at max load.
I prefer the HX