The Scoop on Phenom
Before we get down to the business of benchmarking, here’s the backstory on AMD’s new CPU
Q
How do you pronounce
Phenom?A
It’s fee -nom, not fuh -nom.Q
What advances does Phenom
offer?A
Phenom is AMD’s fi rst
quad-core processor and is
touted as a “true quad core.”
Based on a 65nm process, Phenom uses
an enhanced version of the stellar K8 Athlon
64 core, which features many of the same
“wider and faster” techniques as Intel’s Core
2 Duo. Improvements over the Athlon 64
include the ability to execute SSE instruc-
tions in 128-bit chunks versus 64-bit. Cache
speed gets a bump, as well, with L1 going
from 16 bytes per cycle to 32 bytes per
cycle, and L2 going from 64 bits per cycle
to 128 bits. AMD also spends silicon on
increased fl oating-point performance; a few
new instructions; HyperTransport 3, which
nearly quadruples the bandwidth over previ-
ous implementations; and more L3 cache.Q
What’s meant by “true quad
core”?A
Each Phenom features four
execution cores on
one single, contiguous
die. Architecturally, it’s far more elegant
than Intel’s quad core, which fuses two
dual-core chips in a CPU and forces the
dual-core islands to talk to each other over
the front-side bus. Phenom was designed
from the get-go as a quad chip, and each
core communicates at HyperTransport 3
speeds—several orders of magnitude faster
than Intel’s front-side bus. All the cores can
also share data stored in the L3 cache, so a
core would have to reach out only to the L3
instead of the much slower system RAM in
certain applications. This adds up to a chip
that, on paper, seems to at least equal—if
not exceed—Intel’s Core microarchitecture.Q
What clock speeds will Phenom
come in?A
Just two speed grades will
initially be available: a
2.2GHz Phenom 9500 and a
2.3GHz Phenom 9600. In a few months, two
additional speeds will be offered: a 2.4GHzPhenom 9700 and a 2.6GHz Phenom 9900.
While all feature the same microarchitecture
and cache amounts, there are key differenc-
es. The 9500 and 9600 are much cooler at
95 watts apiece. The 9700 increases to 125
watts and the 9900 hits a Prescott-like heat
dissipation of 140 watts. You do get some-
thing in return, however. The 9900 will run its
HyperTransport link at 4GHz compared to
3.6GHz in the lower-clocked parts, and its
memory controller runs a bit faster at 2GHz
versus 1.8GHz in the others.Q
Why are only two of the four
CPUs available now?A
AMD’s true quad-core
approach sounds great on
paper but it’s also directly
responsible for delays in getting the chip out
and hitting higher clock speeds. We’ll remind
you of the four-leaf clover analogy: While
Intel makes its four-leaf clovers by fusing
a pair of two-leaf clovers, AMD grows all-
natural four-leaf clovers. Unfortunately, the
latter are much harder to come by. AMD has
admitted that problems at the fab are the
reason for the late launch of Barcelona—the
Opteron quad core—and with Phenom. AndCLOCK SPEED 3GHz 3.2GHz 2.3GHz 2.6GHz 2.4GHz 3GHz 3GHz 3.2GHz
L1 CACHE 128KB 128KB 512KB 512KB 128KB 128KB 128KB 128KB
L2 CACHE 2MB 2MB 2MB 2MB 8MB 8MB 12MB 12MB
L3 CACHE N/A N/A 2MB 2MB N/A N/A N/A N/A
FRONT-SIDE
BUS N/A N/A N/A N/A 1,066MHz 1,333MHz 1,333MHz 1,600MHz
EXECUTION
CORES^2 2 444 4 4 4
PROCESS
TECHNOLOGY 90nm 90nm 65nm 65nm 65nm 65nm 45nm 45nm
TRANSISTORS 227 million 227 million 450 million 450 million 582 million 582 million 820 million 820 million
DIE SIZE 230mm^2 235mm^2 285mm^2 285mm^2 286mm^2 286mm^2 214mm^2 214mm^2
PRICE PER 1,000 $300 $220 $283 TBD $266 $1,000 $1,000 TBDINTERFACE Socket F Socket AM2 Socket AM2 Socket AM2 LGA775 LGA775 LGA775 LGA775RATED TDP 125 watts 125 watts 95 watts 140 watts 95 watts 130 watts 130 watts 136 watts
DUAL SOCKET
COMPATIBLE? Yes No No No No No No NoATHLON 64 ATHLON 64 X2 6400+ PHENOM PHENOM INTEL CORE 2 INTEL CORE 2 INTEL CORE 2 INTEL CORE 2
FX-74 BLACK EDITION 9600 9900 QUAD Q6600 EXTREME QX6950 EXTREME QX9650 QX9770THE TOP CPUS FROM AMD AND INTEL COMPARED
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