Cheap And Efficient Dual Core Processors
It is almost incredible to watch the recent price drops in the processor segment. You can get an Athlon 64 X2 3800+ for as little as $80, and only the 6000+ top model exceeds $200. Intel's Core 2 Duo family struts past the Athlon line with the faster products, but you should carefully consider the price premium before purchasing. Since AMD cannot attack Intel in the high-end or the upper mainstream, it dropped prices, so you might get more bang for the buck with AMD. On June 5th it introduced new mainstream CPUs to strike Intel where it is really vulnerable: the low power desktop segment.
The new processors are called simply "Athlon X2", as AMD has decided to drop the "64" suffix. This is a good choice, I believe, because no one really cares much about 64-bit; the new Phenom processors won't carry the "64" label either. It will take many months until 4 GB RAM enters at the upper mainstream, which finally requires a 64-bit operating system to fully utilize the memory. So, 64-bits is a must-have, but by no means a real selling point.
The Athlon X2 BE-2350 runs at 2.1 GHz, while its smaller brother, the BE-2300, operates at 1.9 GHz; they're priced at $90 and $85 respectively. How do these differ from the Athlon 64 X2 4000+ and 3600+, though? All of them are based on the 65 nm DSL SOI process (dual stress liner, silicon on insulator) with 1 MB L2 cache, but the new BE processors are rated for a maximum thermal design power (TDP) of only 45 W.
While Intel had been quick to increase its thermal envelopes to as much as 130 W to support its Pentium 4 and Pentium D hot rods, it reduced the TDP to 65 W in the mainstream with the introduction of the Core 2 Duo. Intel currently does not have a desktop processor to get by with just 45 W, though it does offer two processors under the Pentium brand that might be able to get close to it. The Pentium Dual Core E2140 (1.6 GHz) and E2160 (1.8 GHz) are based on the Core microarchitecture, but they only utilize 1 MB L2 cache and they lack some features.
The 45 W CPU: Athlon X2 BE-2350
As already mentioned, the Athlon X2 BE-2350 is a 65 nm part, based on the current DSL SOI process. AMD currently produces 65 nm products in the new Fab 36 in Dresden, Germany, and it is upgrading Fab 30 to run 65 nm as well. The processors have two cores, each of which can access a 512 kB L2 cache (1 MB total). While Intel utilizes a unified L2 cache architecture, AMD implements a crossbar switch to exchange data between the two L2 caches. Intel's advantage is that each processor can allocate cache dynamically, and thus can access the entire cache area for itself if required. Eventually, designs with dedicated L2 caches and a unified L3 cache will dominate multi core processors.
A memory controller is part of every Athlon 64 processor. In case of the Athlon 64 X2 family for Socket AM2, and for the new Athlon 64 BE as well, this is a DDR2-800 controller, supporting up to four memory modules. AMD also utilizes its well known HyperTransport interface at 1 GHz DDR speed, resulting in an interface bandwidth of 4 GB/s for each of upstream and downstream. As a consequence, the Athlon 64 BE processors can be deployed into all available Socket AM2 motherboards. You will have to upgrade your BIOS to support all processor features, such as Cool'n'Quiet, but the processor will run once your motherboard is able to cope with any 65 nm AMD processor.
Cool'n'Quiet requires BIOS and operating system support. For Windows XP you need a C'n'Q driver, but Vista natively supports this feature. Once enabled, the system will reduce the processor speed and processor voltage in several steps until 1.0 GHz at 1.1 V is reached. In this minimum P-state (performance state), the processor requires the least energy. Athlon platforms proved to be more efficient than Intel platforms, as the integrated memory controller is more energy-efficient than Intel's RAM controllers, which are part of the chipsets. The maximum P-state depends on the processor's maximum clock speed, and the TDP is determined at maximum load at the maximum P-state.
The Athlon X2 BE-2350 is clearly the better choice over the BE-2300, because the per-$1000 price differs by only $5, and the difference is 200 MHz. From an energy requirement standpoint this should not be an issue, as modern processors typically stay in energy-efficient operating modes whenever they run idle.
The Challenger: Intel Pentium Dual Core E2160
The Pentium Dual Core technically has nothing to do with the Pentium 4 or its Pentium D dual core sibling, as it is a stripped down low-cost version of the Core 2 Duo. While Core 2 Duo customers are used to getting 2 MB or 4 MB L2 cache, the Pentium Dual Core has only 1 MB. However, it is still the same efficient, unified L2 cache that we know from the Core 2 Duo. From this standpoint, the Pentium Dual Core also is a state-of-the-art 65 nm processor, and due to its small cache and low clock speed, it should be very efficient as well.
The E2140 is a 1.6 GHz version while the E2160 runs at 1.8 GHz. Both models run at a FSB800 system clock speed, which equals 200 MHz base speed. We purchased a retail kit of the E2160, which comes with a cooler in a nice, blue box. Due to the close relationship between the Pentium Dual Core and the Core 2 Duo, you won't even need a BIOS update to run it on a current Socket 775 motherboard. Pay attention to older motherboards, though - if they don't support the Core 2 Duo, they most likely cannot run a Pentium Dual Core either.
As expected, the test system with the Pentium Dual Core E2160 was efficient, but it could not reach the low energy requirements of the Athlon X2 BE-2350. At the same time, the Pentium came slightly ahead in many of our benchmark runs, and it is more overclockable as well. While the Athlon X2 BE-2350 failed to reach 2.6 GHz reliably, our retail Pentium Dual Core E2160 managed to go as fast as 2.88 GHz reliably. This is particularly impressive as it comes from a default clock speed of 1.8 GHz, while the Athlon X2 runs at 2.1 GHz.
Overclocking: Intel Beats AMD
Scott Wasson over at the Tech Report was lucky with his BE-2350 sample, as he wrote he go it to be "relatively stable" at 3 GHz. Ours didn't want to run as fast; the sample maxed out at 2,520 MHz, and reducing the Hyper Transport speed didn't help either. We had already increased the voltage to 1.4375 V, and applying more reduced our maximum clock speed. Please note that CPU-Z doesn't identify the new processor correctly, which also applies to the voltage. Using an enthusiast-class motherboard could probably help achieving higher clock speeds, but would anyone buy a low-power budget processor to pair it with an expensive high-end motherboard? Probably not. Finally, going from 2.1 GHz to 2.5 GHz represents a 19% overclocking, which is an average result for a mainstream model.
The Intel processor was easily capable of surpassing this: we could reach 2.88 GHz easily by increasing the 200 MHz FSB800 system speed to 320 MHz (~ FSB1280). After increasing the Northbridge voltage from 1.55 V to 1.7 V (default is 1.2 V), we even reached a 3 GHz clock speed. Although we probably wouldn't want to run the highly overclocked system for a longer time, we would certainly go for 2.8 GHz. This equals a 55% overclocking when compared to the stock speed of 1.8 GHz, which is not bad at all!
Platforms With Integrated Graphics
We would have liked to use an Intel G33 chipset motherboard, but the only model we had at our disposal was an early engineering sample. Hence we used the same platforms that powered the sub-$200 processors in the article "Which Is The Best Mainstream CPU?".
AMD: MSI K9AGM2 With AMD 690 Chipset
The AMD motherboard was a MSI K9AGM2, which utilizes the AMD 690 chipset. It is a fully featured MicroATX motherboard, but it only supports two DDR2 DIMMs, with PCI Express x16, PCI Express x1 and two additional 32-bit PCI slots. It has four SATA/300 ports, supports basic RAID modes, and is passively cooled. Thanks to HDMI and D-sub display ports it is also suitable for home theater systems.
Intel: MSI Q965MDO With Q965 Chipset
The Intel platform we chose is the MSI Q965MDO, based on the Q965 chipset. This is the office version of the G965, supporting iAMT and vPro for PC management. The MicroATX board has a four-phase voltage regulator, four DDR2 sockets and six SATA/300 ports. A x16 PCI Express slot, x1 PCI Express and two 32 bit PCI slots await your expansion cards. Unfortunately, this board has neither HDMI nor DVI, which will be added with the next platform generation using the G33 chipset.
|AMD Platform AM2
||MSI K9AGM2, Rev. 1.1
AMD 690G, Bios: 1.1 (03/01/2007)
|Intel Platform S775
||MSI Q965MDO, Rev 1.11
Intel Q965, Bios: 12/19/2006
||Corsair CM2X512-6400C3 XMS6403v1.1
2x 512 MB DDR2-800 (CL 5.0-5-5-15 2T)
|Hard Disk Drive
||Seagate Barracuda 7200.10
1x 400 GB, 7,200 RPM, 16 MB cache, SATA/300
||Gigabyte GO-D1600A (16/48 X) ATA/133
||Intel GMA 3000
AMD Radeon Xpress1250
ATX 2.01, 510 Watt
|System Software & Drivers
||Windows XP Professional 5.10.2600, Service Pack 2
|System Drivers AMD
|Platform Drivers Intel
|Graphics Drivers Intel
Benchmarks And Settings
|Benchmarks and Settings
Audio CD "Terminator II SE", 53 min
Convert wav to aac
||Version 3.97 Beta 2 (12-22-2005)
Audio CD "Terminator II SE", 53 min
wave to mp3
||Version 1.1.2 (Intel P4 MOD)
Version 1.1.2 (Intel AMD MOD)
Audio CD "Terminator II SE", 53 min
wave to ogg
|TMPEG 3.0 Express
||Version: 18.104.22.168 (no Audio)
fist 5 Minutes DVD Terminator 2 SE (704x576) 16:9
Multithreading by rendering
||Version: 6.6 (4 Logical CPUs)
Profile: High Definition Profile
1-pass, 3000 kbit/s
Encoding mode: Insane Quality
Target quantizer: 1.00
(303 MB, 47 Files, 2 Folders)
Compression = Best
Dictionary = 4096 kB
|Autodesk 3D Studio Max
Rendering HTDV 1920x1080
|Adobe Photoshop CS 2
Rendering from 5 Pictures (66 MB, 7 Filters)
|Adobe Acrobat 8 Professional
|Microsoft Office Word 2003
||Version: 11.6568.6568 SP2
1322 pages Word file to PDF
CPU and Memory Tests
Windows Media Player 10.00.00.3646
Windows Media Encoder 9.00.00.2980
|SiSoftware Sandra 2007
CPU Test = CPU Arithmetic / MultiMedia
Memory Test = Bandwidth Benchmark
Memory Latency Test = ns
Conclusion: AMD For Efficiency, Intel For Performance
Even though processor pricing for AMD's entry-level and mainstream models has reached record lows, AMD hasn't hesitated to release additional low-power products at extremely affordable price points. The new Athlon X2 BE-2350 at 2.1 GHz costs less than $100, and thus is cheaper than the closest Intel competitor, the Pentium Dual Core (based on Core 2 technology). From a cost and an energy efficiency standpoint, the 45 W Athlon X2 BE clearly is the best choice today, as you can see from the energy consumption test runs.
The Pentium Dual Core E2160, though, is usually equally fast or slightly faster in many benchmarks. This comes at the cost of slightly higher idle and load power requirements. Our long-term SYSmark 2004 runs prove that the Athlon X2 BE-2350 system required 14% less energy than the Pentium Dual Core E2160 after 60 minutes, and the difference was still 10% after a 90-minute run.
Our tests also showed that the BE-2350 is not a relabeled Athlon 64 X2 4000+, which also has 2x 512 kB L2 cache and 2.1 GHz clock speed. Although the idle power requirements are equal, the regular Athlon 64 X2 consumes 18% more energy under load. The results also underscore the fact that AMD processors have a lower idle power requirements than Intel's CPUs, and that the power requirements under load can be higher.
We also must consider the platform. Motherboards with AMD's 690 chipset typically are slightly cheaper than Intel chipset motherboards based on the G965 or Q965. Many AMD 690 boards also come with HDMI interfaces, which are desirable for home theater PCs. The Intel solutions, particularly those based on the Q965, in exchange offer nice system management options (vPro), which might also be useful.
Finally, there are the results of our overclocking tests: the AMD Athlon X2 BE-2350 2.1 GHz could be overclocked by 19% to 2.5 GHz, while Intel's Pentium Dual Core still was reliable at a core clock speed of 2.88 GHz, 55% over the 1.8 GHz default speed. Users looking for a $100 CPU to build a cheap overclocking solution must go for the Intel product; those who care for efficiency will prefer the AMD Athlon X2 BE-2350.