Power Consumption / Temperature Testing
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 [email protected] in full screen mode.
First and foremost, in order to prevent the new Intel-provided Z77-based DZ77GA-70K motherboard from skewing the power consumption results, we installed the i7-3770K on a freshly flashed Intel DP67BG so that all the LGA1155 chips would be tested on the same motherboard. This way we can isolate the processor as the source for any increases/decreases in power consumption.
The Core i3-2120 is a dual-core 65W part, so it's no surprise that it features the lowest power consumption of this bunch. Given the fact that Sandy Bridge chips already power gates all unused cores, we aren't really surprised to see that there is no grand reduction in idle power consumption for Ivy Bridge. Thankfully, that's not the case when it comes to CPU load. Our shiny new Core i7-3770K needed 17 watts, or roughly 14%, less our i7-2600K sample at full load. That is a pretty solid reduction, and it further reinforces Intel's position as the unquestioned leader of performance per watt. However, we definitely expected to see even better results, perhaps to the tune of 20W-25W less than the previous quad-core 32nm SB parts. As it happens, we did experience a decrease in that range when using the IGP, which you can see below. When it comes to overall system load numbers there is no great revolution, the decrease is pretty much in-line with the drop in CPU load consumption.
Now let's ditch the discrete GPU and take a look at the power consumption when using the new HD Graphics 4000 IGP:
As always, we have to restate that the Sandy Bridge and Ivy Bridge chips in this graph have an almost unfair advantage in the form of the Intel DH67BL motherboard. This Intel-manufactured motherboard has unmatched idle power consumption, easily 10W less than comparable motherboards from the big three motherboard manufacturers. We couldn't do any Ivy Bridge IGP testing on our Intel-provided Z77-based DZ77GA-70K motherboard, since it has no video outputs. Nor would be want to, for the reasons explained above.
With that out of the way, the first thing that pops out is the fact that we did actually record a 26W decrease in CPU load consumption when compared to the i7-2600K. That is pretty much exactly what we were expecting from a quad-core part made on the new 22nm process. While that in itself is noteworthy, it's the very sizeable 32% drop in overall system power consumption that is the most impressive. Intel has almost managed to get this level of CPU and GPU performance under 100 watts...from the wall! We can't wait to see how the mobile parts are going to perform.
For the temperature testing, since we were not given a default cooler from AMD, we used a Thermalright Ultra-120 Extreme with a Thermalright TR-FDB-1600 fan. The ambient temperature was 21°C/69.8°F. The application used to monitor temperatures was AIDA64 2.30.1900. Keep in mind that the thermal sensors in most modern processors are not really accurate at measuring idle temperatures, hence the very small delta between the room temp and the idle results.
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.
As mentioned above, you should obviously take the idle temperatures with a grain of salt, but either way the i7-3770K was exceptionally cool at idle. Athough it might look dire that the Ivy Bridge part experiences such a large spike in temps, given the minimal power consumption difference (67W vs. 64W) between both chips when fully loading the IGP it's not a surprise to see identical temps under this workload. When the CPU is loaded, the i7-3770K did indeed run hotter than the i7-2600K. However, overall we think it's fair to say that the i7-3770K is a cool-running processor at default settings. When overclocked though it's an entirely different story...check out the next page!
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