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This story was printed from CdrInfo.com,
located at http://www.cdrinfo.com.

Appeared on: Friday, December 31, 2004
AMD Athlon 64 FX-55

1. Introduction
AMD Athlon 64 FX-55 - Page 1

- Introduction

Last month we examined the Athlon 64 3800+, a high definition 64-bit state-of-the-art processor from AMD. Since then, AMD has introduced two more processors. The first is the Athlon 64 4000+ which is the successor to the 3800+ and the second, the Athlon FX-55, which we'll be reviewing here.

So what is the real difference between the two family lines, Athlon 64 FX and Athlon 64?

Initially, the difference was quite obvious. The FX processors used the 940-pin socket type whereas the 64 was made for the 754 socket. The FX required the more expensive, yet reliable buffered memory when the 64 could run just fine with plain unbuffered modules. Also, the FX usually had more L2 cache memory and generally ran at higher clock speeds.

However, AMD then introduced us to the 939 socket and having decided to base all of its processors on this socket, the fine line between the two families began to blur. Now it's almost impossible to spot the difference. The 4000+ and 3700+ offer 1Mb of L2 cache and if you compare the two top products from each family, you'll see that the only thing seperating them is 200MHz clock speed. AMD's Athlon 64 4000+ is just an FX-53 with a different name!

Socket 939

Actually, there's another not so obvious difference between them. All Athlon 64 processors ship with their CPU multiplier locked, as opposed to the FX processors that are still left unlocked by AMD.

Model Number


L2 Cache

Socket Type














































Athlon 64 FX processor architecture

Let's examine the FX-55 features more thoroughly.

2. Specifications

AMD Athlon 64 FX-55+ - Page 2

Let's take a quick preview at some of the features the FX-55 offers us:

AMD Athlon 64 FX-55 packaging

CPU Name AMD Athlon 64 FX-55
Codename ClawHammer
CPU Core Frequency 2.60GHz (13x200 with locked multiplier)
Built-In antivirus support(SP2 required) Yes
Simultaneous 32- & 64-bit computing Yes
L1 Cache (Instruction + Data) 128KB (64KB + 64KB)
L2 Cache 1024KB
HyperTransport Yes, one 16x16 link @ 2000 MHz
HyperTransport I/O Bandwidth Up to 8 GB/s
Integrated DDR Memory Controller Yes
Memory Controller Width 128-bit
Memory Supported PC3200, PC2700, PC2100 and PC1600 DDR unbuffered memory
Memory Bandwidth Up to 6.4 GB/s
Total Processor-to-system Bandwidth (HTT plus memory bandwidth) Up to 14.4 GB/s
Process Technology 0.13µ, Strained Silicon-on-insulator technology
Packaging 939-pin organic micro PGA
Thermal Design Power 89W
Die Size 144 mm2
Number of Transistors Approximately 68.5 million

Our NewCastle processor, as recognized by CPU-Z.

Some details about our motherboard and BIOS settings

Our memory timings as seen by CPUZ

The Athlon 64 FX-55 runs by default at a speed of 2.6GHz. That's higher than any AMD processor we have seen so far. It seems the reason for this extra boost in clock speed, originates from the use of strained silicon on the insulator. Strained silicon works by "straining" the lattice of electrical bonds that make up the inside of a chip, pulling them apart slightly. In this way, the amount of drive current needed to power the chip is reduced, allowing the chip to run faster.

The AMD Athlon 64 FX-55 processor

The AMD Athlon 64 FX-55 costs approximately $900. The price might sound completely insane for mainstream users but AMD's FX product line is aiming for "gamers, prosumers and PC enthusiasts".

3. Test System

AMD Athlon 64 FX-55 - Page 3

Here's a rundown of our testbed used to test the 3800+ processor:

System Specifications:
CPU: AMD Athlon 64 FX-55
Cooler: Zalman CNPS7000A-Cu
Motherboard: A8V Deluxe
Power supply: Levicom 500 Watt
VGA: Sapphire 9800pro
Hard Disk Drive: WD800JD 80GB 7200RPM
OS: Windows XP Pro SP2 & Windows XP x64 Edition SP1
Drivers: 4.9 Catalyst
DirectX: v9.0c

Benchmarks & Applications used

4. Prime95

AMD Athlon 64 FX-55 - Page 4



Here are the timings for our Athlon 64 FX-55, the 3800+ and an Intel Pentium 4 2.4GHz.(less is better)

You can see the Intel processor prevails and computes the primes much faster than either of the AMD processors. Even though the FX-55 clock speed is 2.6GHz, 200MHz faster than the Intel CPU, the difference is disappointing. Knowing Athlons' disadvantage in computational benchmarks we expected at least slightly a higher speed from the FX-55.

5. PCMark04

AMD Athlon 64 FX-55 - Page 5




Running the CPU suite benchmark, we obtained the results you can see on the chart above. According to PCMark04, the FX-55 processor offers 8% higher performance than the 3800+.

Let's examine the extended results:


AMD Athlon 64

AMD Athlon 64

File Compression (MB/s)



File Encryption (MB/s)



File Uncompression (MB/s)



Image Processing (MPixels/s)



Grammar Check (KB/s)



File Decryption (MB/s)



Audio Conversion (KB/s)



WMV Video Compression (FPS)



DivX Video Compression (FPS)



With the only exception of Grammar Check, where the 3800+ seems to be a bit faster, the FX-55 produced generally better results.

6. SiSoftware Sandra 2004

AMD Athlon 64 FX-55 - Page 6

SiSoftware Sandra 2004

SiSoftware Sandra (the System ANalyzer, Diagnostic and Reporting Assistant) is an information & diagnostic utility. It should provide most of the information (including undocumented) you need to know about your hardware, software and other devices, whether hardware or software.

CPU Arithmetic


Note:All Intel results are taken as provided by SiSoftware Sandra 2004.

AMD's Athlon FX-55 seems to be lacking in Dhrystone performance compared to the Athlon 64 3800+.


CPU Multimedia


Here the benchmark ran on all Pentiums taking advantage of their x8 SSE2 instructions for integers and x4 SSE2 for floating points, whereas on our AMD it could make use of its x4 Enhanced MMX and SSE instructions for integers.
However it's with floating point calculations that the 3800+ seems to lag in performance, being placed third.

7. Futuremark 3DMark03

AMD Athlon 64 FX-55 - Page 7

Futuremark 3DMark03


GT3 - Troll's Lair GT4 - Mother Nature

++On the following chart you can see the computed 3DMark03 points using our Sapphire 9800 pro Ultimate card on three different processors.

Performance with the FX-55 is slightly improved compared to the 3800+, and both processors left the Intel 2.8GHz behind by 500 3dmarks.

8. Half Life 2 VST

AMD Athlon 64 FX-55 - Page 8

Half Life 2 VST





To measure performance we used the Video Stress Test (VST) that is available in the CounterStrike:Source beta available through Steam. For measuring CPU performance, we set all the details to the lowest level and set the resolution to 640x480.



With almost double the performance of an Intel P4 2.8GHz, the FX-55 is certain to bring the best out of all modern games. In the Half Life 2 Video Stress test, it almost reached the excellent 200 frames per second.

9. Conclusion

AMD Athlon 64 FX-55 - Page 9


The FX-55 is top of AMD's 64-bit family line and probably the best processor available on the market right now. Even though it still lacks in application performance compared to Intel processors, its advantage in games more than makes up for it.

The price of the Athlon FX-55 is its major drawback for the regular computer user. Even though the FX-55 costs approximately $900, which is $200 cheaper than the Intel 3.4GHz Extreme Edition, it is still overpriced compared to its predecessors from the FX family.

-Excellent game performance
-Cheaper than the Intel P4 Extreme Edition

-Unsatisfactory computational performance
-Unaffordable by mid-range computer users

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