First, we need more info on your setup. In particular, do you have aftermarket cooling? Secondly, if you want to know what might have gone wrong with the overclocking, it's vital you say just what you changed. Obviously you raised the base clock to 159 (wierd value btw, you can't get good RAM speeds with that) but did you touch voltages? LLC? C1E? Looks like you left turbo on, unless you have a "K" version CPU.
And lastly, simon is right that the i7 is simply hotter and more power hungry since it has hyperthreading.