AMD Athlon 64 FX-53 & 3800+: Socket 939 Has Arrived

Introduction & Specifications


Since we last took a look at their Athlon 64 FX-53 back in March, AMD has remained relatively quiet.  There was a low profile release of the mid-range Athlon 64 2800+ into the channel, but nothing really new has come from CPU lines at AMD for almost 3 months, which is an eternity in "silicon years".  AMD's relative silence comes to an end today however, with the introduction of four new desktop processors and a new socket standard that brings a common infrastructure to the entire Athlon 64 line-up.  Standard Athlon 64s and high-end Athlon 64 FX processors will both utilize the new 939-pin socket that officially debuts today.

We've got both of AMD's new flagship processors on the HotHardware test-bed, the Socket 939 Athlon 64 FX-53 and the Athlon 64 3800+.  Both of these processors are clocked at 2.4GHz, but they have some fundamental differences.  We'll give you all the detais on their differences and assess their performance on the following pages.

Click any image for an enlarged view.

Specifications: Socket 939 Athlon 64 FX-53 & 3800+
A New Core & A New Socket...
AMD64 - When utilizing the AMD64 Instruction Set Architecture, 64-bit mode is designed to offer:

_Support for 64-bit operating systems to provide full, transparent, and simultaneous 32-bit and 64-bit platform application multitasking.

_A physical address space that can support systems with up to one terabyte of installed RAM, shattering the 4 gigabyte RAM barrier present on all current x86 implementations.

_Sixteen 64-bit general-purpose integer registers that quadruple the general purpose register space available to applications and device drivers.

_Sixteen 128-bit XMM registers for enhanced multimedia performance to double the register space of any current SSE/SSE2 implementation.

Integrated DDR memory controller:
_Allows for a reduction in memory latency, thereby increasing overall system performance.

An advanced HyperTransport link:
_This feature dramatically improves the I/O bandwidth, enabling much faster access to peripherals such as hard drives, USB 2.0, and Gigabit Ethernet cards.

_HyperTransport technology enables higher performance due to a reduced I/O interface throttle.

Large level one (L1) and level 2 (L2) on-die cache:
_With 128 Kbytes of L1 cache and 1 Mbyte or 512K of L2 cache, the AMD Athlon 64 processor is able to excel at performing matrix calculations on arrays.

_Programs that use intensive large matrix calculations will benefit from fitting the entire matrix in the L2 cache.

64-bit processing:
_A 64-bit address and data set enables the processor to process in the terabyte space.

_Many applications improve performance due to the removal of the 32-bit limitations.
Processor core clock-for-clock improvements:
_Including larger TLB (Translation Look-Aside Buffers) with reduced latencies and improved branch prediction through four times the number of bimodal counters in the global history counter, as compared to seventh-generation processors.

_These features drive improvements to the IPC, by delivering a more efficient pipeline for CPU-intensive applications.

_CPU-intensive games benefit from these core improvements.

_Introduction of the SSE2 instruction set, which along with support of 3DNow! Professional, (SSE and 3DNow! Enhanced) completes support for all industry standards.

_32-bit instruction set extensions.

Fab location:
_AMD's Fab 30 wafer fabrication facility in Dresden, Germany

Process Technology:
_.13 micron SOI (silicon-on-insulator) technology

Die Size:
_Newcastle Core - 144mm2
_Clawhammer / Sledgehammer - 193mm2

Transistor count:
_Newcastle Core - Approximately 68.5 million
_Clawhammer / Sledgehammer - 105.9 million

Nominal Voltage:

Athlon 64 FX
Athlon 64


AMD is introducing a few new products today, so we thought we'd put together a chart to make it a bit easier to compare and contrast the differences between the "new" and "old" products.  At the far left and far right, are the older Socket 940 and Socket 754 Athlons, and in the middle four columns you'll find the new processors being introduced today.


There are only three main differences between the Socket 940 and Socket 939 Athlon 64 FX-53 processors.  First, is the packaging - with the new Socket 939 FX-53 AMD has begun using organic packaging with their flagship desktop CPU, as opposed to the ceramic packaging they've used in the past.  Socket 939 CPUs also get a faster HyperTransport link.  The new Socket 939 processors can communicate over the HyperTransport link at 2.0GHz DDR (1GHz actual) that provides up to 8GB/s of total bandwidth.  Socket 940 and 754 processors on the other hand are limited to communicating over the HyperTransport link at 1.6GHz (800MHz actual).  Most importantly, the new Socket 939 Athlon 64 FX-53 no longer requires the use of registered memory.  Standard unbuffered DIMMs will now work with AMD's FX line of processors.

Other than their clock speeds, there aren't any differences to report with regard to the Socket 754 Athlon 64 3700+ and 3400+.  It's when we look at the middle two columns, that things get interesting.  With the new Socket 939 Athlon 64 3800+ and 3500+, AMD is bringing their new "Newcastle" core to the forefront of their mainstream processor line-up.  The "Newcastle" core is equipped with 1/2 of the L2 cache of the previous generation (512K vs. 1MB), but they now have the same 128-bit memory controller that's found in the FX.  Because it has only 1/2 of the cache, the "Newcastle" core is much smaller, and hence less expensive to produce.  It's composed of "only" 68.5 million transistors, as opposed to 105.9 million transistors of the Sledgehammer / Clawhammer core.



Obviously with the switch to a new socket, there are some physical differences with the new processors as well.  Owners of socket 940 motherboards will not be able to use 939-pin CPUs, and if you plan to purchase a socket 939 mobo for an existing Opteron or FX, you'll be out of luck as well.  It isn't just a matter of snipping a single pin to make a 940-pin CPU work in a new socket 939 motherboard.  In the pictures above, we've highlighted the areas of the CPU that have changed.  Numerous pin locations have changed, and the different processor packaging is visible as well (organic vs. ceramic).

The rest of the Athlon 64's feature set remains unchanged.  Like the 3400+, AMD's new socket 939 CPUs feature their "Cool'n'Quiet" technology which is system-level feature that lowers the power consumption of the processor when maximum performance is not needed. With the Cool'n'Quiet feature enabled, the processor will consume less power, and should run cooler and quieter in most circumstances.  Cool'n'Quiet equipped CPUs, provided they are used in the right motherboard, will also have the ability to lower their multiplier (FX's are completely unlocked).  Something to keep in mind in you plan to overclock.  Every Athlon 64 processor is also equipped with Enhanced Virus Protection (EVP) which will be enabled with Windows XP SP2. And until Intel officially launches their EM64T CPUs, AMD's CPUs are the only 64-bit Windows compatible desktop processors currently available.

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