Adding a hard drive to an E520

Today I added a second SATA hard drive to my E520 system. It "clicked"
into the blue plastic bay fine. I connected the power cable fine, but
couldn't find another blue data cable to connect the drive too inside
the system. Is this cable missing? I have an extra one that might work
but I couldn't find a place to plug it into on the motherboard. Where
should the second blue cable be plugged into?

I'd appreciated any help that anyone can provide.

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