Specifications

MAXIMUMPC JANUARY 200532
tECH pREVIEW
Dual-Core Processors
AMD and Intel race to give you two CPUs for the price of one
This year, AMD and Intel will commence
one of the biggest and most interesting
architectural changes in PC history: Man-
ufacturing the first processors that inte-
grate two CPU cores into a single unit.
This development will essentially give us-
ers twice the processing power, but with-
out the extra price of buying two physical
processors, two heatsinks, and an expen-
sive two-processor motherboard.
While it’s true that, upon the debut of
dual-core, the vast majority of applications
won’t be able to take advantage of multiple
CPU cores, we will still see a benefi t in over-
all performance. As an example, one core
will be able to handle all the needs of the
OS, while the other core can perform a com-
pletely separate task, like encoding a movie.
Intel first broke ground on the dual-
core concept back in 2002 with its Hyper-
Threading technology, which presuppos-
es that few applications simultaneously
use all the resources of the CPU core, so
why not make use of the extra resources
for something else? The weakness of Hyper-
Threading is that while the OS gets fooled
into thinking it has two CPUs, it only has
the resources of a single CPU to work with.
If you throw two floating-point heavy apps
at an HT CPU, it may actually run slower as
both programs vie for the same resources.
AMD’s plans
When they debut this summer or fall, dual-core processors will
have two physical cores, each with its own set of available re-
sources. This means you’ll be able to throw two floating-point
apps at the CPU without bogging it down.
Despite the fact that Intel showed off consumer dual-core
CPUs first, AMD is expected to beat Intel to market. The com-
pany recently demonstrated a dual-core Opteron CPU with
each core sporting its own 1MB of L2 cache. While AMD hasn’t
released any specifics for its consumer dual-core CPU, code-
named Toledo, we suspect it will be similar in architecture.
We’re curious to see how AMD deals with the on-die memo-
ry controller that has been such a boon for performance in its
CPUs. AMD will continue to use the controller, but in a dual-core
confi guration, both processor cores will have to share the mem-
ory controller. AMD likely made this choice in order to main-
tain compatibility with existing motherboards, and because of
cost. A dual-core CPU with dual memory controllers operating
in dual-channel mode would require consumers to populate four
separate channels just to get the machine up and running. That’s
costly. It’s not clear at this time whether the shared memory con-
trol will heavily offset the overall performance gain.
AMD says its Opteron dual-core will drop into most Socket 940
motherboards, which implies that the same will be true of Toledo
and most Socket 939 motherboards.
Intel’s big
plans
Intel has been extremely secretive about its
dual-core processor, but it’s been widely
speculated that it will be based on the
Pentium M core. We talked to some anon-
ymous sources at Intel and learned that
the public dual-core demonstration the
company recently gave was running on
the 915 chipset. This strongly suggests
that the CPU involved was P4-based.
Word on the streets is that Intel’s fi rst
dual-core proc, code-named Smithfi eld,
will be two conjoined 90nm Prescott
cores, with plans to eventually move to a
Pentium M-based architecture.
Even though there’s no on-die memo-
ry controller to be shared among Intel’s
dual-core chips, Smithfield will still have
to share the bus and memory controller
if it plugs into the existing 915/925XE
chipset. However, by the time Intel’s
dual-core launches, it’s quite possible its
new chipset, code-named Lakewood (or
Lakeport), will be available and able to ad-
dress the situation.
A little birdie told us that Intel’s top-se-
cret five year plan is to leverage multi-core
processors to re-enter the real-time gaming
graphics market. It sounds crazy when you
consider that current games, which aren’t
multi-threaded, won’t see large perfor-
mance gains on multi-core CPUs. But if the
trend moves toward Renderman-style soft-
ware renderers—running on lots of general purpose CPU cores,
similar to the PlayStation’s Cell architecture—the entire indus-
try could shift away from ATI and nVidia-style discrete graphics
processors. Naturally, this isn’t possible until CPU manufactur-
ers are shipping eight or 16 CPUs on a single die. Could it hap-
pen? Who knows? With its back up against a wall, Intel could
surprise us all.
Possible downside:
power consumption
One encouraging sign in both companies’ early demonstrations
is the possibility that both dual-core CPUs
may work in existing
motherboard designs.
Unfortunately, it’s likely this new generation of processors will
demand more power. Each core requires its own power, so dual-core
CPUs may necessitate bigger power supplies. So while the CPUs may
work with existing chipsets, they’ll only work with motherboards
that can handle the additional power requirements.
When dual-core CPUs are fi nally released, we’ll all know more,
but this much is clear: Performance and processing power aside,
the dual-core proc will be a key ingredient—a vestigial limb of
sorts—in the future evolution of the PC platform.
“AMD and Intel
will commence
one of the
biggest and
most interesting
architectural
changes in PC
history...”