Why does CUDAQ (from CUDALink) download data from Wolfram servers?

I understand why functions like ElementData or CountryData need to download up-to-date data when first launched. However, when trying to use CUDA for the first time in Mathematica, I ran:

Needs["CUDALink`"]; CUDAQ[]

which downloaded data for several minutes. Given that I have a quite fast net connection, that must amount to a really large amount of data. What does Mathematica download in that case? I guess drivers, but how can I check what it downloads?