Graduate School Admissions: Is it worth mentioning in my personal statement for PhD that I have a low (3.3) GPA but a higher (3.67) Major GPA in CS? If I should mention it then what should I write about it or how should I link it with the rest of my statement of purpose? 

(I just suck at courses like history and other core humanities and courses which require you to rote learn a lot of stuff)
I don't know if I'm 100% suitable to answer your question, since I have never applied to a US university; however, I can tell you for sure that in all personal statements I've written for UK universities, I've never mentioned my grades. I don't personally see the point in writing about your grades, since they can find out from your transcripts and from the academic references.