Intel Westmere 32nm Launch & Clarkdale Core i5-661 CPU Review

Power Consumption / Temperature Testing

Power Consumption

For this section, every energy saving feature was enabled in the respective BIOSes and the Windows Vista power plan was changed from High Performance to Balanced.

For our idle test, we let the system idle for 15 minutes and measured the peak wattage through our UPM EM100 power meter.

For our CPU load test, we ran Prime 95 In-place large FFTs on all available threads for 15 minutes, measuring the peak wattage via the UPM EM100 power meter.

For our overall system load test, we ran Prime 95 In-place large FFTs on all available threads for 15 minutes, while simultaneously loading the GPU with OCCT v3.1.0 GPU:OCCT stress test at 1680x1050@60Hz in full screen mode.


As you can see, even with a discrete GPU, the Clarkdale/H55 platform achieves some very impressive power consumption numbers. While the idle figures are not much better than what we saw with Lynnfield, the performance per watt that you are getting when compared to the Pentium Dual-Core and Core 2 Duo setups is hugely improved.

What's really impressive though is what happens you only use the IGP...


Check out those idle numbers, 35W! That's unbelievably low and this is where this new platform excels. It is absolutely ideal for an HTPC or simply a business machine this is left on 24 hours per day, 7 days per week. The system would likely pay for itself over its lifespan when you consider the energy savings compared to an older Pentium 4 or Athlon X2 system.

As you can see, when the IGP is fully loaded it does push the power consumption above that of the low-end discrete GPUs. However, OCCT GPU stress test creates a type of load that you will never encounter in any real-life circumstance.

Temperature Testing

For the temperature testing, we used both the stock Intel Clarkdale CPU cooler and a Thermalright Ultra-120 Extreme (TRUE). The ambient temperature was 20°C/68°F.

Idle CPU + Idle IGP: The system was left to idle for 15 minutes.
Idle GPU + Load IGP: OCCT v3.1.0 GPU stress test was run at 1680x1050 for 15 minutes.
Load CPU + Idle IGP: Prime 95 In-place large FFTs was run for 15 minutes.
Load CPU + Load IGP: Prime 95 In-place large FFTs and OCCT v3.1.0 GPU stress test were run for 15 minutes.


We used Real Temp 3.50 RC6 Beta to collect these temperature figures, and if the results are correct the i5-661's cool running nature is simply betrayed by the mediocre stock cooler that Intel bundles with their new mainstream chips. Having said that, with a high-end CPU cooler like the TRUE the temperatures were extremely low, a testament to the new 32nm process. We believe that passive cooling might definitely be a possibility with Clarkdale, at least in systems with decent case airflow. It was particularly interesting to see how little the IGP affects overall CPU temperatures, even when under the full load of OCCT's GPU stress test.