New
#11
It may be a bad slot, or it may be by design. I would suggest contacting Intel to find out if that is normal behavior with your board. I have heard of these things happening where it does happen by design, but the motherboard manual fails to mention it. Intel's support staff will know for sure.
Also, are all three of your modules from the same kit, or did you buy some at different times/from different manufacturers/with different model numbers?