24-pin ATX main power connector and 4-pin ATX 12V CPU power connector.
LGA775 socket compatible with Intel Pentium 4, Pentium D, and Core 2 Duo (Conroe) processors. rc415t-am motherboard manual
This is the #1 reason people search for the manual. The RC415T-AM uses a compared to modern Intel boards. Here is the official layout (viewed from top, with the missing pin at the top right): 24-pin ATX main power connector and 4-pin ATX