LGA775 vs mPGA478 Package

LGA775 vs mPGA478 (top)

LGA775 vs mPGA478 (bottom)

LGA775 vs mPGA478 (side)

In comparison, the LGA775 package is slightly larger than the
mPGA478 package and the more noticeably the underside of the LGA775 has no pins
and has higher contact densities. The capacitors layout is entirely different

New LGA775 Processors

Pentium 4 3.4 Extreme Edition


Pentium 4 560 (3.6Ghz)

Intel new 775-land "Land Grid Array" package has 775 solder
balls on the underside and is packaged in a Flip-Chip Land Grid Array (FC-LGA4)
package that connects to the motherboard through a LGA775 socket. The LGA775
socket provides I/O, power and ground contacts. The socket contains 775 contacts
arrayed about a cavity in the center of the socket with eutectic solder balls
for surface mounting with the motherboard.

The socket contacts have 1.09 mm X 1.17 mm pitch (X by Y) in a
33×30 grid array. The new package also includes enhanced pin-out for optimizing
the layout of the motherboard and Direct Socket Loading (DSL) to prevent package
pullout and heat sink loading. The benefits of the 775-land LGA package allows
more contact densities as well as better electrical signal integrity for future
higher power, higher frequency processors.

The package includes an integrated heat spreader (IHS) to allow
more better heat transfer to the CPU cooler and also feature a step to interface
with the LGA775 socket load plate. Notice that there is no ventilation hole on
the LGA775 IHS compared to the IHS on the mPGA478.

The Pentium 4 560 (3.6Ghz) features 90nm Prescott core with
12Kµ-Ops of Trace Cache, 16KB of L1 cache and 1MB L2 cache 8-way set
associative. The Pentium 4 Extreme Edition 3.4Ghz features 130nm Gallatin core
with 12Kµ-Ops of Trace Cache, 8KB of L1 cache and 1MB L2 cache 8-way set
associative and 2MB of L3 cache.


LGA775 Socket

There are two official Socket 775 vendors; Foxconn and Tyco.
According to a recent DigiTimes report,  Foxconn being the only volume
supplier, LGA775 connectors are highly priced at US$ 7-8 per unit. However, more
board manufacturers are volume producing LGA775 boards and it likely to push the
price down to US$ 3-4 that results in cheaper 925/915 boards.


LGA775 CPUs Specifications

Processor Number

Core Frequency (Ghz)



Icc (max) (A)
520 2.8 84 1.25 – 1.4 78
530 3.0 84 1.25 – 1.4 78
540 3.2 84 1.25 – 1.4 78
550 3.4 115 1.25 – 1.4 119
560 3.6 115 1.25 – 1.4 119
Extreme Edition 3.4 109.6 1.525 – 1.6 83.9

Intel has unveiled 5 Prescott based processors based on the LGA775 package
with highest speed at 3.6GHz to the lowest at 2.8Ghz and also one Gallatin based
LGA775 Extreme Edition. The new LGA775 Prescott processors all come with model
numbers from 560 (3.6Ghz), 550 (3.4Ghz), 540 (3.2Ghz), 530 (3Ghz) and 520
(2.8Ghz). The TDP is slightly higher at 115W for 560 and 550 compared to103W of
the P4 3.4E. Also the TDP for the LGA775 3.4 Extreme Edition is higher at 109.6W
compared to 102.9W of the 478 3.4 Extreme Edition. Certainly, the processors are
getting hotter and a better thermal design and cooling system have to be put in