Memory slot A doesn't work but slot B does

[Blade Systems]

I recently completed a build with the core i3-4130 and ASRock H81M-DGS with Crucial Ballistix Elite running at DDR3-1600. When I booted the system it said that channel A did not pass CPU memory test. This is confusing because both sticks work when in slot B.

 

[MongoSmash]

Could be a bent pin in the cpu socket throwing errors. Seen that with ASRock boards before.