Smaller chip size means smaller fans means less electricity needed® .....NOW.......B_E_L_I_E_V_E
It's really about the internal brick (PSU). Less energy requirements means less cooling is needed.
There are other things, but as long as the CPU/GPU/Memory board is cool the whole thing doesn't need to be so big.
I'm Unamerica and you can too.
The Official Huge Monster Hunter Thread:









