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Enter the AMD Athlon II X4 635 processor, a mainstream quad-core chip clocked at 2.9GHz and priced at just $120 bucks. Compatible with socket AM3 and AM2+ motherboards, the AMD Athlon II X4 635 is set to be the darling of media PC, home FTP server and budget-minded home PC builders.
80% Rating: 
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AMD Athlon II X4 635 |
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It's not
surprising that AMD has a fight on its hands. Intel continues to
dominate the high-end processor market with its Core i7 chips, forcing AMD to
all but focus its efforts on mainstream $100-150 processors. Then just
when AMD seemed to be 'safe', Intel began making inroads with its
"Clarkdale" Core i3 and Core i5 CPUs into that segment as well. For the
moment AMD is keeping ahead on the price/performance front while Core i3
and Core i5 CPUs suffer from an overly complex platform topology.
Enter the AMD Athlon II X4 635 processor, a mainstream quad-core chip
clocked at 2.9GHz and priced at just $120 bucks. Compatible with socket AM3 and
AM2+ motherboards, the AMD Athlon II X4 635 is set to be the darling of media
PC, home FTP server and budget-minded home PC builders.
Architecturally speaking, the Athlon II X4 635 processor is identical to the AMD's
AII X4 620 chip that PCSTATS tested a few months back, it's just clocked
300MHz faster. If you're familiar with
that processor you know that quad-core Athlon II X4 processors are ideal for
media PC applications when paired with AMD
785G (or upcoming AMD 800-series) motherboard. Put head to head against
an Intel Core i5 or AMD
Phenom II X4 processor they will bring up the rear, but if you're in need of
a good all-around home computer on the tight budget it's good value for the
money. I know we often get fixated on expensive enthusiast grade PC
technology, but if you can't afford that it's nice to know economical
options do exist.
AMD's socket AM3 Athlon II X4 635 chip features 512KB of
L2 cache per core (total of 2MB), but unlike the Phenom II quad-core designs it
has no L3 cache present. Platform compatibility is broad thanks to a DDR2/DDR3
memory controller which makes it possible to install this processor on
motherboards that support DDR2-1066 or DDR3-1333 memory. For PCSTATS
review platform we've selected the Gigabyte GA-MA790FXT-UD5P mobo and
4GB of Corsair XMS3-1600C9 DDR3 RAM. If you're building a new PC from
scratch, it's wise to go the DDR3-route.
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AMD Athlon II X4 635 Processor |
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| Tech
Specs |
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Athlon II X4 635
(quad
core)
Clock: 2.9GHz
L1: (4x) 128KB
L2: (4x)
512KB
L3: none
Multiplier: 14.5x
Package:
938-pin
Socket: AM3 (AM2+)
organic mPGA
Core: 45nm
SOI
Transistor: ~300M
Power: 95W
Vcore:
0.875-1.425V
Cost: $119 USD |
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Manufactured on
a 45nm SOI process at the Global Foundries Fab 1 module in Dresden Germany, the
Athlon II X4 635 has a die size of 169mm2 and
contains 300 million transistors. Although it's some 300MHz faster than the
similar 620 CPU, the Athlon II X4 635 maintains
the same Thermal Design Power (TDP) of 95W.
 AMD's
Athlon II X4 635 is natively a socket AM3 processor, it is also backwards
compatible with socket AM2+ motherboards. It's this backwards compatibility that continues to
make the AMD platform very cost effective and easily upgraded. Right now it's best paired with the AMD 785G chipset, but very shortly it can be paired with AMD's 880G and 890G chipsets.
As you might expect, the
2.9GHz Athlon II X4 635 processor supports full hardware virtualization, so individual cores
can be assigned to virtual machines. Built in virtualization is one of the big features of
Microsoft Windows 7, and it is this that makes running Windows XP Mode inside
of the Windows 7 operating system possible. The Athlon II is also moves C1E low power
states out of the BIOS and onto the CPU hardware.
Retailing for around$125 CDN ($120 USD, £75 GBP), the
Athlon II X4 635 processor is one of the
most affordable quad-core CPUs on the market. Its primary competition will
be coming from AMD's own Phenom II X3 processors and Intel's Core i3 and Core
i5 processors. Let's see how this faster Athlon II compares in the very
competitive mainstream processor field.
Code Name
"Propus"
AMD's quad-core Athlon II X4 635 CPU is built on
the 45nm "Propus" die,
essentially a slimmed-down version of the 45nm "Deneb" core that's been around
since first Phenom II processor. AMD's 'Propus' core consists of four
individual computational cores (4-core, 4-thread) with 512KB of L2 cache each, but unlike "Deneb" this chip contains no L3
cache. Consequently the AII X4 635 die is slightly smaller (169mm2)and a contains
a little more than half the number of transistors, ~300 million.
This is the Athlon
II X4 635 "Propus" die. The L3 cache has been removed, cutting down die
size and reducing the processors power requirements and heat output.
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Having no
L3 cache has a few consequences for the Athlon II X4 635 processor. A large,
fast L3 cache is important for communication between processor cores and
multi-threading efficiency after all. When all four cores are busy processing
threads the L3 cache acts as a pool that feeds the individual L2 caches.
Ultimately this reduces the frequency that the processor has to fetch
information from system memory (system memory) or virtual memory (hard drive),
both of which are orders of magnitude slower than accessing quick on-die L3 cache.
In applications that rely on streaming a
lot of data into all four cores from memory, the lack of L3 cache hurts
the AMD Athlon II X4 635 processor's performance. Moving on, the power meter is hooked up and ready
to measure, so let's take a look at how much juice a PC system built with a
quad-core Athlon II processor actually draws.
Core-by-Core CPU Power Draw
Tests
CPU power draw (expressed in Watts) can be easily
measured by way of total system power if you have a simple electrical power
meter. To determine how much juice the CPU is consuming, we only need to compare
power draw with the processor resting at idle, and with each core at 100% CPU
utilization. For an accurate measurement it's necessary to disable power saving
features and CPU clock speed throttling technologies like Cool 'n' Quiet, EIST
(speedstep) and C1E power states, etc. To stress each core in the processor
individually, PCSTATS uses a free program called Stress
Prime SP2004).
Stress Prime SP2004 is a multi-threaded application
so several iterations can be run concurrently to escalate load on each CPU-core
to 100%utilization (designated CPU-0, CPU-1, CPU-2, etc. using the 'Small FFTs -
stress CPU' test). The power draw for the entire PC system is measured with an
Extech Power Analyzer Datalogger (model 380803). The Extech Power Analyzer is
located between the main 120AC supply and the PC's power supply. An inexpensive
device like the P3 Kill-A-Watt power
meter will do the trick too. Given that
motherboards vary across these test systems this is not a pure measure of CPU
power draw alone, but rather a measurement of the total computer system power
draw, which we can compare for each specific platforms between the CPU idle and
CPU stressed states
| Total System Idle Power
Draw |
| Processor |
Total System Power Draw |
| Intel Pentium 4 540 |
  
150 Watts |
| Intel Pentium D 840 |
165 Watts |
| Intel Pentium D 940 |
168 Watts |
| Intel Core 2 Duo E6600 |
117 Watts |
| Intel Core 2 Duo E6750 |
123 Watts |
| Intel Core 2 Duo E8400 |
131 Watts |
| Intel Core i5 750 |
124
Watts |
| Intel Core i7 920 |
144
Watts |
| AMD Sempron 3600+ |
  
120 Watts |
| AMD Athlon64 4000+ |
163 Watts |
| AMD Athlon64 FX-60 |
127 Watts |
| AMD Athlon64 X2 4800+ |
143 Watts |
| AMD Athlon64 X2 5000+ |
156 Watts |
| AMD Athlon64 FX-62 |
168 Watts |
| AMD Athlon II X2 240e |
122
Watts |
| AMD Athlon II X2 250 |
128
Watts |
| AMD Athlon II X3 435 |
128
Watts |
| AMD Athlon II X4 620 |
130 Watts
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AMD Athlon II X4 635 |
   127
Watts |
| AMD Phenom II X2 550 Black Edition |
145
Watts |
| AMD Phenom II X2 555 Black Edition |
143
Watts |
| AMD Phenom II X3 720 |
155 Watts |
| AMD Phenom II X4 910e |
131
Watts |
| AMD Phenom II X4 955 |
148 Watts |
| AMD Phenom II X4 965 - 125W TDP |
150
Watts |
| AMD Phenom II X4 965 - 140TDP |
154 Watts
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Even with
a couple hundred extra MHz under the hood, the Athlon II X4 635 CPU idles at 127
Watts, a hair lower than the Athlon II X4 620.
We'll see where the power draw figures stand once
the system is under stress, for each of the Athlon II X4 635's four processing
cores right after the jump...
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