Judging by the performance, the graphics core in Sandy bridge processors could actually replace the entry-level graphics cards easily. Of course, in this case we should also benefit in terms of power consumption. We decided to perform our traditional power consumption tests in order to estimate our potential gain from this replacement.
The graphs below show the full power draw of the computer (without the monitor) measured after the power supply. It is the total of the power consumption of all the system components. The PSU's efficiency is not taken into account. The CPUs are loaded by running the 64-bit LinX 0.6.4 utility. Graphics cores were loaded using FurMark 1.8.2 utility. Moreover, we enabled C1E and Enhanced Intel SpeedStep power-saving technologies to ensure that computer power draw in idle mode was measured correctly.
We have already stressed several times before that Sandy Bridge processors are very energy-efficient in idle mode. The use of the integrated graphics core doesn’t take away this advantage. Systems built on second-generation Core processors with the integrated graphics core consume 5-10 W of power less in idle mode than any other platforms.
LGA1155 systems with integrated graphics also consume less power in processor-heavy tasks. This is quite logical, since Sandy bridge computational cores currently offer the best performance-per-watt ratio. And the graphics core built into these processors is more energy-efficient than external graphics accelerators and other integrated cores at least due to the fact that it is manufactured using the latest 32 nm process.
Heavy graphics load shows very clearly that Sandy Bridge graphics is very energy-efficient. Its performance is close to that of entry-level graphics accelerators, while the power consumption is 10-15 W lower. By the way, note that Intel HD Graphics 2000 and Intel HD Graphics 3000 modifications (the latter has twice as many execution units as the former) differ by only 6 W in power consumption, and the 35% overclocking of the graphics core frequency has even less effect on the power consumption.
Complex work load applied to the computational and graphics resources of the system lets Core i5-2500K compete on equal terms with the platform utilizing Core i5-2500K and its integrated graphics core. However, since the Intel HD Graphics 3000 core built into this processor performs better than the above mentioned graphics card, there is nothing remarkable here. There is another interesting thing about it: the peak power consumption of contemporary integrated platforms using latest generation high-performance processors doesn’t exceed 90 W. so, even the regular (non-energy-efficient) Core i5 modifications can easily be part of a compact home system or HTPC.
Another type of complex load is HD video playback. Due to a special hardware video decoder in the new Sandy Bridge processors, there is barely any load on the computational CPU cores. As a result, the power consumption of Sandy Bridge systems with any graphics core modification is only 6 W higher during video playback than the power consumption in idle mode. As a result, HD video playback in systems like that requires even less energy than some platforms would need for idle mode alone.