www.algoblast.com
The absolute ressource regarding technical music.
I suggest bands like : Pavor ( awesome ),
Capharnaum,
Coprofago ( death mainly based on tempo, somewhat like Meshuggah but with jazzy interludes ),
Cephalectomy,
Daath ( not totally technical, but strange nonetheless ),
Korum,
Fuck The Facts ( not death, but an awesome technical grind band that'll blast your head, the singer's sick, especially since it's a girl... ),
Gory Blister,
Ion Dissonance ( math deathcore ),
Kralizec ( melodic death/black hybrid, totally awesome ),
Lethargy ( not totally death, but it had to be metioned ! ),
Theory in Practice ( why wasn't that mentioned ? They rule. )
And I second every other band that was named...