AMD Athlon 64 3800+: Probing the Venice Core

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Although desktop dual-core processors from AMD are on the horizon, engineers there are still hard at work refining their single-core processor designs. The latest revision to the Athlon 64 core, internally code named "Venice", recently made it way onto the mass market, carrying a "Rev. E" moniker.  With the Venice core, AMD has integrated SSE3 multimedia instruction sets into the Athlon 64, and have made some additions and enhancements to the integrated memory controller as well.  The changes to the Integrated Memory controller include:

·_Mismatched DIMM support (ability to configure and use different size DIMMs on the same channel)
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_Improved memory mapping (more efficient use of memory space)
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_Improved memory loading (can fully populating the memory with double-bank DIMMs with no slow down)

When a new Rev. E Athlon 64 3800+ processor recently arrived in the lab, we found that it performed at the same level as previous revisions to the A64 core in our standard suite of benchmarks. But we were eager to see if this new revision of AMD's .09 micron silicon was a better performer in another sense. Particularly, we wanted to see if the Venice core would overclock higher than previous revisions, and also wanted to monitor its operating temperature and power consumption in the process. The information on the proceeding pages contains the results of our experiments...

Specifications: Socket 939 Athlon 64 3800+
Tweakin' The Process...
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 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) - Newcastle
_.09 micron SOI (silicon-on-insulator) - Winchester
_.09 micron SOI (silicon-on-insulator) - Venice

Die Size:
_Newcastle Core - 144mm2
_Winchester - 84mm2
_Venice - 84mm2

Transistor count:
_Newcastle Core - Approximately - 68.5 million
_Winchester Core - Approximately - 68.5 million
_Venice Core - Approximately - 68.5 million

Nominal Voltage:
_1.50v (Newcastle)
_1.40v (Winchester & Venice)

Athlon 64

 


To accurately compare the overclocking potential, thermal characteristics, and power consumption of a .13 micron - Newcastle core based Athlon 64 3800+, to a new .09 micron - Venice core based Athlon 64 3800+, we had to take some precautions, to ensure that the comparisons would be legitimate.  First off, we tested each processor in the exact same test bed; only the CPU itself was swapped out between the tests. Secondly, the room where the testing was conducted was climate controlled, and remained at a constant 70oF (21oC) throughout. We also used the exact same heatsink and fan combo, and the same thermal compound on each CPU. And any "smart fan" controls were disabled to prevent the CPU cooling fan from thottling at lower temperatures. The tests were conducted with all components mounted in a mid-tower case, but with one of the side-panels removed.  The Gigabyte K8NXP-SLI motherboard we used for testing was updated to the latest BIOS (vF6), all voltages and bus speeds were set manually, and AMD's Cool 'n Quiet technology was disabled.

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