The Lian Li was one of the first 100% aluminum cases, it had a lower
ambient temp than all the other cases I put against it.
That's quite possible due to case design instead of metal
type. FWIW, I have two identical cases made of steel and
aluminum (Turbo Gamer, made by same manufacturer as some
Antec cases) which are same temp with same parts... at one
point I swapped cases merely because I had front bay panels
for one that matched the color of the other case better.
This was with a
very over clocked AMD system with an over clocked Matrox video card, so
it was a system that you could have used as a space heater. Also the
differences were slight, but there were differences. There were lots of
reviews that showed this and that's when the all aluminum cases became
quite the rage.
Aluminum is not cooler. Another urban myth. You'd have to
have the chassis ambient (air) temp substantially higher
than the room air temp for the difference in aluminum's
conduction to matter. If your case's air temp is THAT high,
it was far too high for a system to run in it in the first
place. It is easy enough to tell if the case is helping-
feel the side of it... If it doesn't feel warm, there's not
enough of a temp difference to matter. If it does feel
warm, you need more chassis cooling as even the bare minimal
AMD and Intel recommendations will not let a chassis get
that hot unless the front bezel were a solid restrictive
panel.