** Super Micro Computer's SMCI.O shares jump 15% to $29.34 in extended trading

** AI server maker in its preliminary fourth-quarter earnings update says it expects adjusted gross margin in the range of 15% to 17%, nearly double the forecast of a 8.2%-8.4% range it had issued previously

** Co says it was helped by a "favorable customer and product mix"

** SMCI also logged record order backlog in excess of $60 billion, but projected Q4 revenue at the lower end of its $11 billion to $12.5 billion expectation

** Analysts tracking the stock rate it "hold" on average; median PT is $39 - data compiled by LSEG

** SMCI is down ~13% so far this year