Add a 2.5 inch SSD to a MAC Pro(2007) what do I need?

This worked perfectly, in my 2009 model

http://eshop.macsales.com/item/Other%20World%20Computing/MMP35T25/

I'm not sure, but you may need thhis for the 2007

http://eshop.macsales.com/item/NewerTech/ADPTADRV/

I think yours is the same as the 2009, but you'll have to look inside.

Looking at some youtube video of the 2007 model, I'm 99% sure yours has four drive bays like mine.

If that's correct, the first one I listed is the one you need.

If you are unbearably cheap like me, you can install it on a standard sled by removing the Drive mounting screws on the left side of the sled, and substituting a single 3mm Optical/2.5" drive mounting screw (no captive washer) and a flat washer using the outboard mounting screw position.

To install, you must hand-guide the drive into position while using a bright light to assure proper connector mating.

Alternatively, many Users are happy with the Icy Dock mounting system. There may be slightly different models for the two different sleds (2008 and previous, 2009 and later).

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RE: Cooling:

OWC shows installation into bay #1. I suggest you should have a regular hard drive in bay 1 if possible, to act as a dam to improve airflow directly through the fan below. The poorest cooling is at bay #4, so that is a great place to put your low power SSD.

The Mac Pro will boot from a drive in any drive bay, just specify in

System preferences > Startup Disk.

It appears that the first item linked, the OWC mount pro, works only in 2009 and later models, which use a slightly different sled.

For 2008 and previous, you would need the other item, the Newertech adaptadrive.

Maybe call OWC.

That alternate sled is a crisp solution. The only reason it is not the #1 recommendation is the price.

OWC used to offer a similar 2.5" sled (at a similar expensive price) before they replaced it with the "OWC Mount Pro" for 2009 and later.