"Socket 775, also called Socket T or LGA775, is a Land Grid Array (LGA) socket used by several generations of desktop Intel microprocessors starting from Pentium 4 and up to Core 2 Quad / Core 2 Extreme families. The LGA775 supports Intel CPUs from 1.8 to 3.8 GHz with Front-Side Bus frequencies ranging from 533 MHz to 1600 MHz. This socket superseded socket 478.

The Socket 775 differs from all earlier x86 sockets in the sense that it doesn't have pin holes. Instead, it has 775 gold-plated contacts arranged as a grid 33 x 30 contacts with 15 x 14 section de-populated in the center, with one corner contact and 4 contacts on two sides on the socket removed. After the processor is placed into the socket it has to be secured by pushing down socket's load lever. The socket 775 is guaranteed to last at least 20 insert cycles.

The size of the socket LGA775 is 1.48" x 1.48" (3.75 cm x 3.75 cm), or about 15% larger than the size of socket 478. At the same time the socket 775 has 60% more contacts. The increase in the number of contacts without equivalent increase of socket size was achieved by reducing the distance between contacts. Another advantage of the new socket design is the lower resistance of the contacts, which reduces the amount of heat generated by socket and socket contacts.

LF-LGA775 socket is RoHS-compliant version of LGA775 socket"

Я глянул для Xeon написано Socket 775 для Intel Core 2 Quad тоже Socket 775. Все я не проверял процессоры.