I'm about to buy a new mid 2012 13 inch MBP, and I don't know which one to choose. If I choose the 2.5GHz dual-core Intel Core i5, I'll definitely add the 8GB RAM upgrade. But my biggest concern is which one feels more comfortable in temperature. In other words, which one is cooler? Does the 2.9Ghz 2-core Intel Core i7 get hotter running the fan more often at a higher speed because it has a faster processor? Or it doesn't have to do anything with it?