What is the power consumption of a C7000v2 modem?

Some indication is available here http://www.tpcdb.com/list.php?type=30 - value does certainly vary based on WiFi usage, number of active GbE links, upstream channel power, ...

> What is the power consumption of a C7000v2 modem?

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Read.  Look for "Technical
Specifications" and "Power adapter".  Or, look at the ratings on the
label on the C7000v2 and/or its power adapter.

      12V * 3.5A = 42W

   That would be an upper bound.  I'd expect that actually measuring the
power consumption under realistic conditions would be more reliable.
For example:

      http://www.p3international.com/products/p4400.html

> I need this info so I can determine how long my UPS will provide
> power.

   Be careful with your assumptions.  A typical UPS is rated for use
near its maximum output, and its efficiency may drop significantly under
a light load.  If you already have your "my UPS", then I'd run the
experiment.