How do you change a PRAM battery for Mac Pro early 2011

In the 42 lb silver tower Mac Pro from 2006 thru 2012, you remove the graphics card from its slot and the battery is behind it on the mainboard. Use a bright light and understand what is retaining the battery in its holder before acting, because breaking the battery holder will ruin your afternoon.

what year? 2011, 2021? Mac Pro, MacBook Pro? There is no early Mac Pro 2011, or 2021. There's a 2008, 2009, 2010, 2012, Late 2013, and 2019.

A MacBook Pro 2011 model does not have a separate PRAM backup battery -- it uses the main battery as the backup battery as well.

If you allow the main battery to go flat, the parameters will be scrambled. You will need to reset:

Reset NVRAM or PRAM on your Mac - Apple Support

.

If you have a Notebook computer, such as a MacBook Pro 2011 model. it does not have a separate PRAM backup battery -- it uses the main battery as the backup battery as well.

To add to Grant Bennet-Alder's reply, the following is an image of where the battery is located on the Mac Pro system board: