How to make sure my GPU is being used when building lighting?

I would like Lightmass/Swarm/Lighting rebuild to run as fast as possible.
I wonder if it is utilizing my GPU or just my CPU, and if I could get faster lighting builds done by recruiting the GPUs.
If I can, how do I find out if the Lighting Rebuild is using my GPUs as well as my CPUs?

Here are my system specs:

Processor: Intel(R) Core™ i7-3770 CPU @ 3.40GHz
OS: Windows 8 64-bit
RAM: 8 GB
System Type: 64-bit Operating System, x64-based processor
Graphics adaptor: NVIDIA GeForce GTX 650 Ti BOOST (2GB edition)
Integrated graphics adaptor: Intel(R) HD Graphics 4000
UAC: On
Visual Studio 2012 Express for Windows Desktop
DirectX SDK June 2010

Hi Aaron,

Lightmass performs its computations on the CPU so your GPU won’t affect total lighting build time.

Would the GPU not do a better job than a cpu? nvidias cuda is pretty powerful stuff, im sure theres a reason for not using it but i don’t think epic have every given an explanation why they wont use gpus?

Would it be possible to in future to make use of GPU for lightmass baking ? Some offline renderes use OpenCL.
IT would be very useful and reduced building times to fraction of what can they can be today.

Improving lighting work flow is something we plan to work on. That includes reducing the amount of time it takes and doing it in the background so you can continue using the editor while it’s running. I don’t know whether that means we will use the GPU for lighting computations but we will consider all possibilities in terms of improving work flow.

Hypothetically speaking, would it be practical to have the GPU assist with light builds? What kinds of limitations would there be having the GPU assist, or do all of the work?