AMD Turion 64 on the Desktop

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METHODOLOGY

A total of six processors were chosen for testing: The four Turion 64 processors mentioned above, an Athlon 64 3200+ (Newcastle), and a Pentium M 770. Specifications for the six processors are listed in a table below. Together, the six processors should help answer these two questions:

1. How much power does the Turion 64 line require, and how does power consumption change across the range of models?
2. How does the Turion 64 measure up in terms of performance-per-watt in comparison to other processors on the market?

PROCESSOR COMPARISON
Processor	Clock Speed	L2 Cache	Default Vcore	TDP	Supported Instruction Set Extensions
Turion 64 MT-34	1.8 GHz	1 MB	1.2V	25W	MMX, 3DNow!, SSE, SSE2, SSE3, AMD64, NX-Bit
Turion 64 MT-40	2.2 GHz
Turion 64 ML-40	2.2 GHz		1.35V	35W
Turion 64 ML-44	2.4 GHz
Athlon 64 3200+	2.2 GHz	512 KB	1.5V	89W	MMX, 3DNow!, SSE, SSE2 AMD64, NX-Bit
Pentium M 770	2.13 GHz	2 MB	1.372V	27W	MMX, SSE, SSE2, NX-Bit

Test tools included:

• AC power was measured with an Extech Power Analyzer / Data Logger 380803 power meter.
• High accuracy Extech MM560 True RMS multimeter.
• Several multimeters of reasonable precision.
• High precision LTS 25-NP Current Sensor (to read the AUX12V current), courtesy of Intel.
• A Fluke 36 Clamp Meter
• Processor voltage was monitored using SpeedFan 4.27
• Athlon 64 and Turion 64 specifics were documented using the utility A64 TCaseMax v1.18
• CrystalCPUID, a utility for setting and modifying clock speed and voltage.

Two test systems were built: One for the AMD processors, and one for the Pentium M. The same power supply was used in both to eliminate any differences in power supply efficiency.

System	AMD Socket 754	Intel Socket 479
Power	FSP Green PS FSP400-60GLN 400W power supply
Motherboard	MSI RS482M-IL	AOpen i915Ga-HFS
RAM	512 MB OCZ Gold PC3200 DDR SDRAM (one stick)	1024 MB Corsair DDR2 SDRAM (one stick)
Heatsink	Zalman CNPS7000CU, plugged into the motherboard	Stock AOpen heatsink, plugged into the motherboard
HDD	Seagate Momentus 5400.3	Hitachi E7K100

The AOpen i915Ga-HFS used here is the only full-ATX motherboard for Pentium-M that we know of. It is packed with features, such as:

• HDTV/TV Support - YPbPr connector, Svideo connector and D4 (Japan use only) connector to attain the highest image quality on 1080i or 720p resolution.
• Supports DVI Output - On-board, along with VGA.
• Gigabit LAN on-board
• PCI Express x16 Graphics slot
• Dual Channel DDR2 533 memory support

The only downside is that it retains the small proprietary CPU heatsink mounting holes from the earlier micro-ATX i915GMm-HFS board we reviewed last year, along with a similarly small Northbridge HSF.

AOpen i915Ga-HFS is the only ATX board for P-M we know of.

All processors were measured in three states to establish the full range of power consumption:

• Idle
• Idle with Cool'n'Quiet, PowerNow!, or SpeedStep enabled
• Under heavy load using CPUBurn to stress the processor

Two different measurements were taken in each state:

• Total AC power consumed by the system as a whole.
• DC power drawn by the processor from the +12V AUX connector.

A fancy power meter from Extech helped us keep track of AC power.

AC power was measured to obtain a power profile of each system as a whole. By design, this includes power lost in the power supply itself during conversion from AC to DC. Most power supplies become less efficient as they approach zero output. At the low power loads of these systems, the power conversion loss may account for as much as 50% of the total system power. Measurements for AC power were read off of the digital display on the Extech power meter.

However, the DC power measurements are a bit more involved. A high precision current sensor is plugged directly into the +12V AUX connector on the motherboard, so that all power through this connection must pass through the power meter. The line voltage (nominally +12V) and the current are measured with multimeters, and multiplied together to get the total power running through the connection. Assuming that the CPU only draws power through +12V AUX connection and nothing else does, this tells us the amount of power consumed by the CPU plus whatever power is lost to inefficiencies in the voltage regulators on the motherboard. This assumption was confirmed by using the Fluke 36 clamp meter, which showed that no other voltage lines showed significant increases when the CPU was under load.

An custom-built shunt featuring a LTS 25-NP current sensor allowed us...

...to measure voltage and current on the +12V AUX connector that powers the CPU.
The final accuracy for this power calculation is better than °1W, maybe as good as °0.1W.

To repeat, the DC power measurements do not take the efficiency of the voltage regular module (VRM) on the motherboard into account.

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