I just pickup some 2x4 from home depot, not exactly know what kind of lumber, and cut it about 35" , secured to the 3 studs with 1/4" X 3-1/2" lag screws with 2 on each stud (top-bottom). The lag screws has only about 1" of bite into the stud through the 2x4.
The server rack I am going to mount on has a backing plate hook which is secured to the 2x4 only with four 1/4" x 3" lag screws, the bottom is not secured to anything, the total weight I going to put in is around 150 lbs.
Drilled pilot hole for all screws going into wood.
Would the 2x4 hold those weight? I am thinking add 2 triangle shelf bracket on the bottom.