About two weeks ago, I had bought a G750JX with a GTX 770M but wasn't satisfied, so I returned it and got another model, this time with a 780M.

When comparing the two, there are a few glaring differences I noticed:

Hard Drive
OLD (JX): much quieter (both !TB 5400 RPM, model unknown)

Fan Noise
OLD: System much quieter, fan almost inaudible even during heavy load
NEW: Minimum fan noise approx. equal to max fan noise of old system

Screen
OLD: Decent, even hues and illumination, quite smooth look for a laptop screen
NEW: Very discernible pixels, especially when background is white - cells almost impossible to ignore, very bothersome to view

Build
NEW: At a glance, seems much thicker, and has a slanted, rather than flat, build

Granted, the old one had Windows 8 pre-installed, while the new one had something called 'Free Dos', and I had to go out of my way to find [semi-]suitable drivers to make things work on Windows 7.

Could the fan, screen and hard drives be that different? I really didn't expect a world of difference between one model and another in a series that promises cool and quiet operation, especially when UPGRADING. Any insight and tips are welcome, thanks!