SEPTEMBER 2004 MA XIMUMPC 31
The Parts
new Intel
925X chipset, three
PCI Express slots, dual-channel
DDR2 support up to DDR2/600 speeds,
and overclocking features that make it
such a badass mobo we think it should
have its own soundtrack.
http://www.asus.comCPU: Intel 3.6GHz
Pentium 4 560
Selecting this year’s CPU was likely the
most difficult decision in the history of the
Dream Machine process. We had three
potential chips in mind: Intel’s Pentium 4
560 (that’s a 3.6GHz Prescott in the real
world), the 3.4GHz Pentium 4 Extreme
Edition, and AMD’s stellar Athlon 64 FX-53
in Socket 939.
Each CPU has its strengths and weak-
nesses. The Athlon 64 FX-53 is generally
acknowledged to be faster in games while
the Extreme Edition is better in most appli-
cations. Both Intel chips are faster in mul-
titasking—when you run at least two CPU-
intensive apps at the same time—thanks
to Hyper-Threading.
The Intel side of the coin, however, had
a decided advantage given our desire
to build a next-gen PC: PCI Express and
DDR2 goodness. We tried mightily, but
we just couldn’t acquire an AMD-based
motherboard that supported PCI Express.
And because the memory controller is
integrated into these CPU cores, it would
have taken the fabrication of a brand-
new core to support DDR2 RAM. After
AMD declined to crank up its fab in order
to crank out a single chip for us, the deci-
sion became clear.
With our choice narrowed to two
chips, we thought it would have been
easy for the Pentium 4 Extreme Edition
to supplant the Pentium 4 560. After
all, we recommended that people not
buy the Prescott a few months ago in
Socket 478 trim when it ran at 3.2GHz.
Surprisingly, however, the P4 560 turned
in some decent numbers that made it
extremely competitive with the Extreme
Edition CPU. Was it the new chipset? Or
maybe a secret spin of the core by Intelthat corrected the sub-par performance
at 3.2GHz? Or maybe the Prescott simply
needs higher velocity clock speeds to
keep its 30-stage pipeline well fed?
Ultimately, what mattered most
was the chip’s overclocking ability. We
couldn’t squeeze many extra clock cycles
out of our Extreme Edition, but we wereable to push the 3.6GHz P4 to a stable
3.97GHz with simple air-cooling. We
won’t call it 4.0GHz, but we think it’s fair
to call it 4GHz. At this speed, the machine
ran through no less than 10 iterations
of SYSmark2004 plus a battery of other
benchmarks without a single hiccup.
http://www.intel.comPCI Express isn’t just a fancy new name
stamped onto old technology. PCI Express
ushers in a new era for computing that’s a
quantum leap over the 12-year-old parallel
PCI (peripheral component interconnect)
bus. That’s right—12 years!
The average desktop’s PCI slots top out
at 133MB/s. While extended flavors of PCI
can hit higher speeds, the technology is
rapidly approaching its limits because you
can only push data in a parallel interface
so far before you encounter problems.
Think of the data as a car on the free-
way. The freeway itself is the PCI bus.
Now, put five cars abreast and have them
drive down a twisting, turning freeway,
staying within two feet of each other at
all times. At 50mph, it’s easy. Now get the
cars to try to maintain the two-foot dis-
tance at 150mph. The higher speed makes
it harder for the cars—our stand-in for
data—to maintain their synchronicity.
This is the problem with parallelbusses on the PC. On the PCI Express
freeway, just one car is moving down the
freeway, which is one lane wide. Since
this car can drive down the freeway with-
out the need to maintain close contact
with four other cars, it can easily drive
at 100mph, 200mph, or 300mph. One of
the advantages of PCI Express, however,
is that it also allows you to run multiple
lanes. But, because each lane operates
independently of the others, they don’t
have the same limitations as the parallel
PCI bus.
Each PCI Express lane can support
data transfer rates of 200MB/s. Early moth-
erboards will support a single x16 slot
(pronounced “by sixteen”) for graphics
cards and between two and three x1 slots
for expansion cards. As PCI Express cards
are introduced, we expect PCI to largely
become a legacy slot—much like ISA,
which it replaced.Inside the Dream Machine: PCI Express
A brand-new bus architecture results in an astronomic increase
in data transfer ratesPCI Express x1new Intel
925X chipset, three
PCI Express slots, dual-channel
DDR2 support up to DDR2/600 speeds,
and overclocking features that make it
such a badass mobo we think it shouldthat corrected the sub-par performance
at 3.2GHz? Or maybe the Prescott simply
needs higher velocity clock speeds to
keep its 30-stage pipeline well fed?
Ultimately, what mattered most
was the chip’s overclocking ability. We
couldn’t squeeze many extra clock cycles
out of our Extreme Edition, but we wereInside the Dream Machine: PCI Express
PCI Express x16