Those with the Velocity X2 Solo using the "extra" Sata slot

I have no personal experience with this product, but perhaps it could help you.

http://www.transintl.com/dx4-for-mac-pro-2006-2008-no-drives.html



It replaces a drive sled and enables you to mount four 2.5" drives above your PCIe cards (while still mounting the 3.5" drive previously on the sled).

If you do a search for "transintl dx4" there is a youtube video.

I linked to the MP 2008 version on the assumption your signature is up to date.

Good luck.


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Edit:

One more thing. I've personally shoved a 2.5" SSD in the empty space in the optical bay between the actual drives and the handle you pull on. It is snug and doesn't move around, but it would probably offend some people's sensibilities. The optical drive screws do scratch the SSD case if you care about that sort of thing. The primary benefit to this solution is that it is free and you can do it right now if your SATA cable is long enough to route into the optical bay.

 

http://pindelski.org/Photography/2013/09/13/mac-pro-2009-part-xviii/

Not sure if that helps - it's for the Apricorn PCI card with a SATA socket.

 

Interesting. I had not seen that before. Rather pricey tho.

 

Another possible solution....

Trans intl also has another solution called double decker:

http://www.transintl.com/index.php/mac-pro-enhancements/double-decker.html


I personally have that DX4 thing. It works really well, and we house 6 SSDs in it (two just friction slot in there).

For your needs, I would go with the double decker.