Click above to reach "Hypnotize" played with a metronome. This is another System of a Down, one half-step lower, drop D tuning on a 1982 USA made Gibson Special.
Click above to reach "Toxicity" played through with only a metronome. This is yet another System of a Down, one whole-step lower, drop D tuning on a 2008 Epiphone Wilshire reissue.
Here's a fun combo using SOAD's whole-step lower drop D tuning on a Samick Artist Slimline Blues Guitar.