I'm not a gamer but I've found this: http/gpuboss.com/gpus/GeForce-GT-740M-vs-GeForce-840M
Note that the 840M is 1GB DDR3 and you mencioned a 2GB DDR3 840M. If with half the memory 840M performe just a little lower in some tests an won others, then with the same amount of memory and a higher clock the 840M 2GB will be better. Check if the 840M is really 2Gb dedicated
gt 740m laptop i5 4200m - http/tinyurl.com/ot5agjb
the i7 840m laptop's 23.87 mm thick vs 27.9mm thickness for the one with i5 & 740m. I thought larger is the laptop better is the air flow and heat dissipation. Am i wrong ? Also the i7 is an ulv processor, what kind of performance can i expect from it. Is turbo boost dependable- can i expect it to work through 2 to 3 years of usage, i have no experience of it as my old lappy has only a pdc processor. Please advise.
It´s almost the same stuff with "details" that pop my attention in sound quality and optical drive:
Envy i5: Beats Audio with Highest Quality Sound, HD Audio, Integrated Speaker Bar Quad Speakers with Internal Subwoofer. Optical Drive Not Available
Pavilion i7: Beats Audio with Highest Quality Sound, Dual Speakers. Optical Drive SuperMulti DVD RW Drive with Dual Layer Support
You've told in the inicial post you want it to for moderate gaming... Seems that this are more then enough.