# EZ Computer Guru Q: RMUs

**URL:** <https://boards.straightdope.com/t/ez-computer-guru-q-rmus/557047>\
**Category:** Factual Questions\
**Created:** [October 13, 2010, 8:34pm UTC](https://boards.straightdope.com/t/ez-computer-guru-q-rmus/557047 "2010-10-13T20:34:02Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [October 13, 2010, 8:34pm UTC](https://boards.straightdope.com/t/ez-computer-guru-q-rmus/557047/1 "2010-10-13T20:34:02Z")

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Besides marking off a computer server rack in increments of whole RMUs, what other method might be used? I saw a 42U rack with numbers in the middle part of the rack ranging from 50 to 90. (I failed to notice what number is at the top). Any clue what increments these might be?

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [November 7, 2010, 12:23pm UTC](https://boards.straightdope.com/t/ez-computer-guru-q-rmus/557047/2 "2010-11-07T12:23:54Z")

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If anyone else should read this thread, I figured out the nubers were identifying each screw hole along the length of the post of the rack. Three screw holes = 1 U = 1.75 inches.

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**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\
**Post date:** [November 7, 2010, 1:03pm UTC](https://boards.straightdope.com/t/ez-computer-guru-q-rmus/557047/3 "2010-11-07T13:03:24Z")

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Did they number the screw holes? The 50th hole is going to be just a bit short of the mid point on the rack.