Si son XFX, creo que son estas:
http://www.viperlair.com/reviews/video/other/xfx/nv4x/6600/
Si son Built by Nvidia...pues ni idea![Stick Out Tongue :p :p](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
http://www.viperlair.com/reviews/video/other/xfx/nv4x/6600/
Si son Built by Nvidia...pues ni idea