Black screen on boot with 3.7.16 on Dell inspiron

This is not about my main post's laptop but

I just want to mention the discovery I got just now.
I have a Macbook Air 8GB and a damaged ASUS 4GB laptop at home, Here are the results:

Mac:
-stable: blackscreen with "boot error" written <-right after select which to BOOT
-beta: successfully get into the desktop, no problem with anything. brightness working. one thing i dont understand is that, when i use "free" on terminal, it shows i only have 2gb ram, with 0 swap.

ASUS:
-stable: graphic error on regular live boot, not trying the other yet
-beta: successfully get into the desktop, with "ndivia" option on boot selection, brightness working.

I dont have any spare monitor, neither at my workplace or home.

as i can see, every machine has its own problem, lol.