december 2007 MAXIMUMPC 55
Q
What exactly is a Penryn?A
Penryn is the “family” name
for Intel’s follow-up to its 65nm
Core 2-lineage CPUs. For consum-
ers, Wolfdale will be the dual-core Penryn,
Yorkfield will be the quad-core version, and
Harpertown will be the quad-core Xeon
workstation CPU.
The big enhancement is the process
shrink from 65nm to 45nm. Intel calls its
move to a 45nm process the “biggest
change to computer chips in 40 years.”
Intel’s tendency toward self-aggrandizement
aside, the 45nm process is a significant
jump forward, allowing twice as many tran-
sistors to fit in the space of a 65nm chip.
The 45nm process also uses high-k gate
dialectics. Not to be confused with L. Ron
Hubbard’s Dianetics, the high-k gate using
hafnium oxide replaces the silicon dioxide
gate that’s been in use since the 1960s. The
new transistor leaks less energy, produces
less heat, and is able to switch faster than a
silicon dioxide transistor by 20 percent. This
boils down to smaller, faster, more power-
efficient CPU cores. How much smaller? The
previous Core 2 Extreme quad cores packed
582 million transistors within a space of
286mm^2. The Yorkfield quad core packs 820
million transistors into 214mm^2.Q
So what else is new under the
hood?A
Penryn is more than a simple die
shrink. The new CPUs are based
on the Core 2 microarchitecture
with a few tweaks that Intel hopes will
keep it ahead of AMD. The headliner of
these tweaks is the new SSE4 instruc-
tion set designed for media encoding and
high-performance computing. Also new is
a Super Shuffle Engine, which increases
the speed of many SSE media-encoding
instructions by doubling the processing
units from 64-bit to 128-bit.
Penryn also includes a new Fast Radix-16
Divider that pretty much doubles the divisionmath speed. Intel also reportedly boosted
virtual machine performance by as much
as 25 to 75 percent. And Intel added a
new feature called Dynamic Acceleration
Technology that essentially overclocks one
of the cores when the others are sleeping.
The new chip also makes use of all the
physical space freed up by the die shrink.
(Imagine if all the stuff in your garage shrunk
by 50 percent!) That’s what accounts for the
beefed up L2 cache, which at 6MB per core
is a 50 percent increase over the L2 in 65nm
quad cores. The larger L2 cache helps in
numerous ways, but its biggest contribution
is in ameliorating the potential performance
hit caused by the ancient shared front-side
bus architecture Intel uses for communica-
tion between cores. To keep the front-side
bus from bogging down, the large and very
efficient L2 cache ensures that the CPU has
ample data close at hand so it won’t be data
starved. While Intel has certainly proved that
the FSB strategy is still workable, the com-
pany has stated it plans to adopt an on-die
memory controller in its next CPU.Q
How significant is the new SSE4
instruction set?A
Instruction sets in CPUs always
garner the most attention but,
sadly, are usually the last feature
to actually add performance benefits. While
the Fast Radix-16 Divider and the Super
Shuffle Engine in Penryn will increase the
performance on many existing applications,
the 47 new instructions in SSE4 will not give
you any performance boost until applica-The Nuts
and Bolts
of It
We ask, and answer, the questions on every
PC enthusiast’s mindIntel’s 45nm die shrink allows engineers to pack nearly twice the number of
transistors into the same space as a 65nm CPU.Clock Speed 3GHz 3.2GHz 2.93GHz 3GHz 3GHz
L1 Cache 128KB 128KB 64KB 64KB 64KB
L2 Cache 2MB 2MB 4MB 8MB total 12MB total
Front-side Bus n/a n/a 1,066MHz 1,333MHz 1,333MHz
Execution Cores 2 2 2 4 4
Process
Technology^ 90nm^ 90nm 65nm 65nm^ 45nm
Transistors 227 million 227 million 291 million 582 million 820 million
Die size 230mm^2 235mm^2 142mm^2 286mm^2 214mm^2
Price per 1,000 $300 $220 $1,000 $ 1,000 $1,000
Interface Socket F Socket AM2 LGA775 LGA775 LGA775
TDP 125 watts 125 watts 130 watts 130 watts 130 watts
Dual socket
compatible? Yes^ No^ No^ No^ No^athlon 64 athlon 64 x2 6400+ Intel Core 2 Intel Core 2 Intel Core 2
fx-74 blaCk edItIon extreme x6800 extreme qx6850 extreme qx9650specs
model