Fatal error: Out of memory in csv.php

I installed piwik 1.12 in Windows (a dedicated box with 32GB RAM installed, not shared) IIS6 using FastCGI (PHP v.5.5.2, x86 non thread safe), MySql v.5.6. While exporting Visitor Log in CSV format, I get this error:

“Fatal error: Out of memory (allocated 1987575808) (tried to allocate 3408360 bytes) in E:\piwik\core\DataTable\Renderer\Csv.php on line 287”

The Visitor Log has about 16,000+ rows for the date I tried to export (I know it since I could export in XML format without this error). I have modified “memory_limit” in php php.ini file to allow more memory usage, “API_datatable_default_limit” to be no limit in piwik global.ini file since I need all records, but still no luck.

Are there any settings I need to change in order to make this happen? My observation is that it seems always fail while hitting 2GB of RAM.

Thank you all for help,