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 expected, the A8-3870K features nearly identical power consumption figures as the A8-3850. The numbers aren't quite Sandy Bridge good, but then again Llano chips do have 1.45 billion transistors, more than any other mainstream-level processor.
When overclocked, the A8-3870K has slightly higher power consumption than the similarly-clocked 3.6GHz Phenom II X4 980, but the Llano chip obviously has a huge chunk of its die dedicated to graphics. Since it was designed to be used in a simple system without a discrete GPU, let’s take a look at the power consumption when using the IGP.
First let's restate that the Sandy 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.
Once again, the A8-3870K's default power consumption numbers are basically identical to the A8-3850. The idle results are good, but when you load up the CPU power consumption rises greatly, and it is not really competitive with its main competition, the Core i3-2100 series. Thankfully, the power consumption doesn’t rise much when you also tax the integrated GPU, so overall you end up with a system that peaks at about 145W. This is obviously excellent when compared to the two configurations with dedicated GPUs, and when you consider the level of performance that you are getting in the graphics department.
When overclocked the figures do rise substantially, but you are getting a nice 20% performance boost in most applications and a 30-40% gain in games.
Temperature Testing
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 HWiNFO v3.82-1300. 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.
AMD are known for making cool-running processors, and the A-series APUs are no different. Our A8-3870 sample was remarkably cool when idle, and barely warmed up when we were fully loading the integrated GPU. Even when both CPU and GPU portions where loaded, the temperature just barely broke the 40°C mark.
When overclocked and overvolted the CPU and GPU obviously put out a lot more heat, but even then we did not record any temps above 55°C. You definitely don't need to spend more than $30 on an aftermarket CPU cooler to get this chip cool when overclocked.
