Q6600 Different Core temps

Hi, i have an Intel Quad Core Q6600 2.4 GHZ (stock), and i changed out the dell heatsink to an zalman heatsink. I used all the parts except the square looking mouting bracket that goes underneath the motherboard as my stock one held the screws fine. Also i got the artc silver thermal paste.

http://www.newegg.com/Product/Show [...] 2fHeatsink

I installed everest and my temp reading are as following (these are idle temps, while im typing this lol):
Core 1: 32°C
Core 2: 33°C
Core 3: 23°C
Core 4: 32°C

So my question is why is there an difference of 10°C between core 2 and core 3. Any help will be greatly appreciated. Thanks in advance.

Each core might be loaded differently. It's that or the fab job was done better or worse, or even the heat sensors...