Is a SATA splitter a thing? [duplicate]

Is it possible to split the data plug of a SATA connection? I have 2 hard drives and an optical drive I want to use simultaneously, but my computer only has 2 SATA connections. I can power the extra hard drive from another PSU I have, so power isn't an issue. The question is if its possible to split the data connection.

No. What you might be able to do (check the documentation) is to connect a SATA RAID enclosure to your one SATA port, then configure the enclosure to "see" two separate volumes. Depending on the hardware, you could even get "hot-plug" capability thrown in.

I seem to remember a (Lindy?) gimmick I found on Amazon that basically did this, without even the enclosure - just a Y-cable with a box in the middle.

But very often this "trick" requires that you first format both of your hard drives to make them "known" to the enclosure. While this might sometimes be even more desirable (i.e. one can "see" a larger single volume, which might be preferred over two separate volumes)... in your case, it might not.