Check their site site to be sure.
But IIRC no it doesn't have the HDCP support, that only became standard on the GX2 and 7950 series.
For the GF7900 you have to look for it, and the only ones I remember are the GF7900 GS HDCP from their refreshes. The GF7600GS and 7900GS got the HDCP IIRC, until the GF7950 series came along.
But check to be sure, since I'm not.