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AMD Athlon 64 X2 3800+ Review - Part 1 - 11/14/05

AMD Performance Guide
AMD Builder Guide
AA-64 Architecture

Microsoft & x86-64
Prescott Prospects
Athlon 64 Utilities
Athlon 64 Drivers

Hammer Presentation
Hammer Patent and

White Paper (pdf)
64 Bits For What?

AMD on Athlon 64
Can't be better start for finding the perfect Athlon 64 SFF barebone...
Tech Links
Hot Links
Socket 939 1 2 3 4 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
AMD Athlon X2 3800+
Dual Core Review - Part 1

With the latest stepping of the dual processor series, AMD dishes up the Manchester core to set new standards in energy efficiency and price/performance ratio. Taking advantage of the proverbial excellent gaming and floating point performance and stripping the dual cores of 50% of their hard-earned cache in combination with a frequency sweetspot of 2.0 GHz results in a killer CPU at a reasonable price tag. Arguably, there are cheaper processors on the market, there are faster cores out there (as measured in clock frequency) and there are "the others" but after wrapping up this review, there is nothing out there that combines that many positive features as the Manchester running at 2.0 GHz, using the moniker X2-3800+.

Parallel processing is becoming more and more mainstream. Intel is doing it, AMD is doing it and whoever is left is basically left behind -- unless they are doing it as well. Conventional wisdom has it, though, that there is no such thing as a free lunch and dual cores come with a price. The extra investment is, as we have shown in a few earlier articles, not only a one time shot for the purchasing price, on the contrary, Intel's D-series sets new records in terms of heat dissipation and power consumption, resulting in a somewhat increased electrical bill that, arguably, can offset the heating bill during the colder seasons, but also increase the AC costs.

The X2-series introduced by AMD looks somewhat better in that respect. However, especially in comparison with the award-winning energy efficiency of the Venice core, the introductory offers of AMD's dual core architecture did not look so great either. On the other hand, high power consumption is not necessarily a must, since power management should be able to take care of most of the overhead. Unless there is really load on both cores, there is no reason to keep everything up and running at full bore.

The wafer in the background actually contains "Toledo" dies, characterized by the large L2 cache.

Then there was the issue with the cache and its burning of energy. SRAMs are using power and fast SRAMs gobbling power for breakfast. The role of the SRAM-based L2 cache in power consumption is probably best illustrated in our comparisons of the Clawhammer vs. Newcastle cores running at the same core speed, which shows almost 25% reduction in overall power consumption after throwing out half of the L2 cache.

When we were looking at the Toledo, therefore, it was not overly surprising to see the power consumption shooting up way beyond that of two hypothetical Venice cores at the same speed, the extra cache on each "hemi" alone would account for that already. The San Diego core exemplified in the FX57, on the other hand churned out even more than half of the Toledo-based 4800+, however, bear in mind that the numbers we have reflect a core speed of over 2.8 real GHz, which makes the power consumption shoot through the roof by default.

Given the above, the strategy for a low power - high performance CPU would, therefore, have to be to use an existing design of the Manchester core with 512 kB L2 cache per "hemi" and throttle down the clock speed until a sweet spot is reached. The sweet spot in this case encompasses low voltage operation as well. A case in point is the Mancunian candidate we have on the test bench today, codenamed X2-3800+ and running at 1.3V, good enough to keep 2,000 MHz core-speed alive and kicking. The only question is, how good is the power / performance ratio really?

* the revised memory controller allows to run the memory in pseudosynchronous DDR433 / 466 mode
** The AMD Athlon 64 X2 4200 and 4600 are available in Manchester core and in Toledo core with 1/2 of the L2 cache disabled for yield increase. In the latter case, the transistor count is 229 million.
*** The AMD Athlon 64 X2 4200 and 4600 are available in Manchester core and in Toledo core with 1/2 of the L2 cache disabled for yield increase. In the latter case, the dis size is 199 mm2.
**** In general all AMD (and Intel) power and thermal specs are generated for the top of the line processor in a given stepping to serve as guidelines for the mainboard manufacturers and system integrators, showing worst case scenario. Therefore, lower performance processors will have greatly reduced power consumption compared to the specs when measured in real life environments.

Test Configurations

To put things into perspective, we are using dual and single core configurations for comparison along with a dual processor Opteron system. The point is not to say that one is better than the other, rather it is to give some idea where a given system would currently be, and whether there is really any need for upgrading or not. Every processor and every system has its own strengths and weaknesses and depending on one's preferences, some of the issues will be irrelevant whereas others may influence a purchasing decision -- or not.

Dual Core Special

Athlon 64 Socket 754
Athlon 64 Socket 939
Athlon 64 Chipsets
Athlon 64 Live News
Athlon 64 Cooling
Athlon 64 OPN & ID
Athlon 64 Overclocking
Athlon 64 Packaging
Athlon 64 Special
Athlon 64 FX 51 Special
Athlon 64 FX 53 Special
Athlon 64 FX 55 Special
Athlon 64 FX 57 Special
Athlon 64 FX 60 Special
Athlon 64 2800+ Special
Athlon 64 3000+ Special
Athlon 64 3200+ Special
Athlon 64 3400+ Special
Athlon 64 3500+ Special
Athlon 64 3800+ Special
Athlon 64 4000+ Special
Athlon 64 X2 4200+ Special
Athlon 64 X2 4400+ Special
Athlon 64 X2 4600+ Special
Athlon 64 X2 4800+ Special
AMD64 Special
Opteron Special
Sempron Special
Turion 64 Special
Socket 939 Packaging
AMD Roadmap
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We have all the Athlon 64 notebooks you're looking for!
Your best source for AMD Athlon 64, barebones, DDR, nForce2, nForce3, nForce4, motherboards, notebooks, Opteron, Sempron & Turion 64 information
Frequency: 2.0GHz
Cache Sizes: 2 x ( 64KB L1 Data + 64KB L1 Instruction Cache / 512 kB L2 Cache (Exclusive))
CPU to MC: 2.0 GHz
Memory Controller: Integrated 128-bit memory controller
(arbitrated through System Request Interface between cores)
Supported Memory: PC1600, PC2100, PC2700, PC3200 and PC4000* DDR memory
HyperTransport Links: 1
HyperTransport Spec: 2GHz (2x 1000MHz / DDR)
Effective data bandwidth: 14.4 GB/sec [8GB/sec x1 HyperTransport link + 6.4GB/sec memory bandwidth]
Packaging: 939-pin organic micro-PGA
Fab location: AMD's Fab 30 wafer fabrication facility in Dresden, Germany
Process Technology: 90nm (.09-micron) Silicon on Insulator (SOI)
Approx. Transistor count: 154 million**
Approx. Die Size: 142 mm2 ***
Nominal Voltage: 1.30 V
Max Thermal Power: 110 W****
Max Icc (processor current): 85 A
Max Ambient Case Temp: 49-63 degrees Celsius
"Socket939" Platform:
AMD Athlon64 X2 3800+, AMD Athlon64 X2 4800+
Athlon64 4000+, 3800+, 3500+, AMD Athlon64 FX57
2 x 512 MB OCZ PC3200 Platinum DDR modules
"Socket754" Platform:
AMD Athlon64 3200+, 3400+
3800+, 3500+
2 x 512 MB OCZ PC3200 Platinum DDR modules
Dual "Socket 940" Platform*****:
AMD Opteron 252
4 x 512 MB Mushkin PC3200 Registered ECC DDR modules
"Socket940" Platform**:
AMD Opteron 150
4 x 512 MB Mushkin PC3200 Registered ECC DDR modules
"955X" Platform:
Intel D955XBK mainboard
Intel Pentium4 LGA 775 840 Extreme Edition, 840D, 820D, 670
2 x 512MB OCZ PC2 5400 DDR2 modules
"925XE" Platform:
Intel Pentium4 LGA 775 3.46 Extreme Edition, Intel P4 660, ExtremeEdition 3.73GHz
2 x 512MB OCZ PC2 5400 DDR2 modules
"925X" Platform:
Intel Pentium4 LGA 775 3.4 Extreme Edition
P4 LGA 560; 550
2 x 512MB OCZ PC2 5400 DDR2 modules
Sapphire RADEON X800XT / 2 x eVGA GeForce 6600 GT (SLI platform only)
Maxtor Maxline3 250GB SATA HDD
"875" Platform:
Intel Pentium4 3.4 Extreme Edition
P4 3.4C / 3.4E
4 x 256 MB OCZ PC3700 EB DDR modules
"855" Platform:
Intel Pentium M 735
2 x 512MB OCZ ZB DDR modules
ASUS RADEON AX800Pro (modded) (Socket 940/Intel 875/INtel 855)
2 x WD 36GB Raptor HDD RAID Level0 (Socket 940)
***** The next generation Socket 940 processors will no longer need Registered ECC memory, rather standard DDR400 will suffice.
Benchmark Overview

Software 32-bit

Windows XP Corporate Edition
Service Pack 2
SiSoft Sandra 2005
Cachemem 2.65
Lightwave [8]
3dsmax 5.1
Cinebench 2003
FarCry (Patch 1.3)
Abbyy FineReader
Caligari TrueSpace 5.1

SiSoft Sandra

In the synthetic Multimedia benchmark, the X2 3800+ scales better than the clock speed would suggest - which was to be expected.

The memory benchmark shows the dependency of the memory bandwidth on the core clock speed of the CPU. In addition, we increased the memory speed to 433 (pink) and as a result of the necessary synchronizers and intermediate fifos, the bandwidth further drops -- quite a bit. All benchmark runs were done at 2:2:2:7 latency settings.

For quick reference, the P4 670 is indicated in red, the P4 820D in blue and the Athlon64 X2-3800+ in green. For detailed scores, please visit the relevant pages in this article.
Part 2
Part 3
Part 4
Part 5
Part 6
Top Price
Part 2 >>
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