Power Consumption And Efficiency
Our benchmark suite is automated so that tests run in the same order each time, with the same delays between commands. There is even a period of idle time injected at the end to capture the reality that even high-end workstations aren’t under load 24x7. At the end of that idle period, the workstation shuts itself down automatically.
As that’s happening, we log power consumption. The above chart represents power use through the run. We also get a sense for how long each configuration takes to finish the batch file and turn itself off, given the length of each line. Right away it’s clear that two Xeon E5-2687W v2s complete our battery of benchmarks faster than first-gen -2687Ws, and they do it using less energy.
Averaging the data points together shows that, indeed, the newer Xeons use 20 W less through our suite. That’s pretty remarkable considering:
- The new Xeons operate at higher clock rates under load and in lightly-threaded apps.
- The new Xeons have 5 MB more of shared L3 cache each.
- The average results have a ton of single-threaded work and idle time factored in; considering threaded workloads-only would exacerbate the difference.
Of course, the averages themselves don’t take into account how quickly a given platform got its job done, dropped to idle, and stopped using power. For that, we need to create a unit of energy by multiplying wattage by the time it takes to finish our workload.
Those single-threaded tasks and that idle time give Intel’s Core i7 a big advantage when it comes to average power consumption. However, because the two Xeon E5-2687W v2s are so much faster, they gain quite a bit of ground when we factor performance into the equation.
Compared to first-gen E5s, the new -2687W v2s use less power and are faster. That’s a recipe for an efficiency sweep, reflected in a 42 Wh advantage in our benchmark suite.