Measuring power in a story like this is never going to be an exercise in precision. If you run a processor-limited test, graphics get ignored. A graphics-heavy benchmark might overemphasize the GPU at the expense of the rest of the platform.
Logging the SPECapc 3ds Max 9 benchmark seemed like a good compromise, though. Not only does the test have its own CPU render component to complement the graphics tests, but it also seemed to show Intel’s HD Graphics P3000/3000 engine in a fairly balanced light.
What the SPECapc score doesn’t tell you is how much faster the Quadro FX 580 wraps this test up. The entire thing takes just over 15 minutes with discrete graphics. It takes more than 25 minutes on either the Xeon E3 or Core i7 platforms using Intel’s processor graphics.
If you flatten each of those three lines, you discover that both systems with Intel CPUs and Intel graphics average about 84 W over the course of the run. Dropping the add-in card increases average system power use to nearly 96 W (that’s not bad, by the way, though it suggests only moderate utilization of the GPU).
Unfortunately, those averages mean very little, aside from the fact that adding a graphics cards increases power use (duh). You have to multiply them by the fraction of an hour it takes the workload to complete. Do that and the story turns around. Because the Intel systems take so long to finish their job, they use more than 35 watt-hours. Adding the discrete card, however, drops that figure to 25 watt-hours.
Now, I’m not trying to say a workstation with a Xeon and a Quadro card in it is going to reflect that power graph for everyone. Many, many professional workloads are exclusively processor-bound. Dumping an add-in board is only going to increase power consumption. Log a run through Premiere Pro CS5, for example, and the Nvidia chip will spin idle, unused.
So really, our figures are most useful for, one, showing that the Xeon E3-1275 has the exact same power profile as a Core i7-2600K and two, demonstrating that although an all-integrated solution is more power-friendly at any given point in time, it can also drag its feet to the point where adding discrete graphics would actually be more power-friendly in a given workload.