Notebook Test System, Vital Signs and Power Consumption
We tested Intel's Merom Mobile Core 2 Duo in our Asus Z96JS whitebook that we showed you here recently. It provided a solid test platform to easily compare and contrast performance characteristics of Intel's legacy Core Duo (Dothan) architecture versus Merom (Core 2 Duo).
ASUS Z96JS Whitebook
- 2.33 GHz Intel Core 2 Duo T7600
- 2.16GHz Intel Core Duo T2600
- 1.83GHz Intel Core Duo T2400
- Intel 945PM Chipset
- 2 x 512MB - 1GB DDR2 667MHz memory
- 256MB ATI Mobility Radeon X1600
- 8x DVD+/-RW with dual-layer support
- 80GB 7200RPM Hard Drive (SATA/150)
- 15.4" WXGA display (native 1280x800)
- Intel Pro 3945 a/b/g WiFi card
- 10/100/1000 Ethernet
- 6 cell Li-Ion battery
Taking a look at readings from CPU-Z, we see similarities between the older Core Duo architecture and Core 2 Duo. Below are screen-shots from CPU-Z with a Core Duo T2600 (Yonah) chip, a Core 2 Duo T7600 (Merom) processor and finally a Core 2 Duo E6700 (Conroe) chip.
Merom Idle - 1GHz
Merom Load 2.33GHz
First, the similarities. For starters, both Yonah and Merom run on a 667MHz FSB. In the case of our T2600 Yonah chip, a 166MHz clock is driven into a X13 multiplier for the core CPU speed and a X4 multiplier for the FSB. Our T7600 Merom is clocked likewise with the exception of a X14 multiplier for its core speed of 2.33GHz versus the X13 multiplier and core speed of the 2.16GHz T2600. And that's where the similarities end for the mobile processors. The rest of the architecture for Merom is much more akin (or should we say "clone" even) to Conroe.
First and foremost, Mobile Core 2 Duo and Desktop chips support Intel's updated SSE instruction set that CPU-Z likes to call SSE4. Also, both Merom and Conroe can process EM64T instructions for Windows XP 64-bit support. And finally both Merom and Conroe have the same 4MB L2 cache and 32K Instruction and 32K Data cache architectures, although there are 2MB variants coming as well. The primary differences between the Mobile Core 2 Duo and Desktop chips are their operating voltages -- 1.163V observed here for Merom and 1.32V observed for Conroe -- along with a much faster FSB for Conroe at 1066Mhz.
But does this upgrade in Intel's Mobile CPU architecture come with a power consumption cost?
Clock-tick for clock-tick the answer is a resounding "No". In the graph here, we've listed total system power consumption for our Asus Z96JS whitebook at idle speeds for the processor and then again under 100% CPU load. We took readings on power draw from the system's AC adapter connected to our lab's wall outlet. Some quick math reveals that Merom's 2.33GHz clock speed advantage over the T2600 (Yonah) 2.16GHz chip almost directly correlates to its additional power consumption. To be exact, our Core 2 Duo T7600 is clocked around 8% faster than the Core Duo T2600 and likewise only draws about 9-10% more juice.
When you consider the fact that both Yonah and Merom are both built on Intel's 65nm process and that Merom has an additional 2MB of L2 cache along with EM64T support, Intel's design engineering triumph with Core 2 Duo becomes crystal clear. Intel's Mobile Core 2 Duo offers more processing power, capacity, features, and does so at power parity versus their legacy mobile Core Duo architecture. Against the backdrop of Intel's Pentium 4 Netburst architecture, Conroe's advancements resulted in impressive and massive gains from a performance-per-watt perspective. In kind, Merom seems to offer similar gains versus the already power-efficient Yonah architecture. Let's take a look at the hard data next and confirm these statements.