CPU and GPU Power Consumption Comparisons
CPU Power Consumption
For our power consumption testing we decided to approach it from two different angles. First, the standard CPU-based power consumption that will see how the x86 cores in the AMD A8-3850 APU compare to the Core i3-2100 at both idle and load conditions. Idle was taken at the Windows desktop after about 2-3 minutes of inactivity with all power savings options in the BIOS enabled. The load power consumption numbers were taken from running CineBench 10 in its multi-threaded mode to max out all available CPU cores.
A note on the results: both of the top two results (the AMD A8-3850 and the Core i3-2100) were taken WITHOUT the GTX 275 discrete graphics card installed. The others DID have the card installed.
Idle results for the A8-3850 compared to the Core i3-2100 are pretty good with the AMD APU using less energy at this point. The load conditions aren’t as good with the APU pulling down an additional 49 watts in CB10. Considering the APU is supposed to be a 100 watt part and the Core i3-2100 is a 65 watt CPU, those are larger than expected gaps.
And if you take a look at the AMD A8-3850 compared to the Sandy Bridge based Core i7-2600K, it uses nearly as much power and it does not have a discrete GPU installed while the 2600K does. Despite the poor x86 performance of the A8-3850 APU it seems to be using a lot of power while falling behind.
GPU Power Consumption
Next we will look at the power consumption of the integrated graphics on both the A8-3850 and the Core i3-2100. For this we used Left 4 Dead 2 which is actually a good game that pushes both the GPU and the CPU and thus this should represent a "complete" load on each of the processors. While I am sure the CPU and GPU portions of each part are not fully maximized I imagine this is about close as it will get in the real world.
At stock settings and 1333 MHz memory speeds, the AMD A8-3850 based system uses a total of 41.4 watts more power than the Core i3-2100 running the same game. Obviously, the performance of L4D2 is world’s better on the AMD system than on the Intel Core i3 but that performance does come at the cost of power. In my estimation though (and surely everyone else’s) that extra power is more than efficiently utilized in that 3x improved frame rate.
Also, in case you were curious about how power consumption changed as the memory speed increased on our AMD APU system, you can see those results as well. Even at the extremes we only saw a 3.6% gap in power draw.
With the discrete Radeon HD 6670 installed and running on both the Core i3-2100 and AMD A8-3850 (without Dual Graphics enabled) the AMD system used a total of 31 watts more power getting us closer to that 35 watt rated difference between the two processors.