The first system we have for comparison against the PandaBoard ES hardware is an Intel Atom 330 NetTop from MSI. This system has an Intel Atom 330 that is a dual-core part operating at 1.60GHz plus Hyper Threading to provide four logical cores. The system also has 1GB of RAM, ATI Mobility Radeon HD 4300 graphics, and a 250GB Samsung HDD. This is not the perfect comparison due to the system using an HDD rather than a Secure Digital card, etc, but the results are quite apparent anyhow. The comparison systems were all running stock, clean installations of Ubuntu 12.04 LTS for the respective architecture. All of the systems were also tested without an X.Org Server running.
When the Intel Atom 330 NetTop was idling, 29 Watts was being drawn, which was just below the power of the 12-core ARM cluster.
With the Embarrassingly Parallel workload, the Atom 330 system was burning through 33.6 Watts for the system with the dual-core Atom that also boasts Hyper Threading -- again, not too far off from the power consumption of all six PandaBoard ES units.
The Atom 330 had an EP.C result of 19.7 Mop/s. For comparison, a single PandaBoard ES with two cores being used for the NPB test had an average of 10.3 Mop/s or four cores were at 18.4 Mop/s. In other words, a single 1.2GHz Cortex-A9 core is close to a single core of an Atom 330 x86 processor. Twelve 1.2GHz ARM cores produced 53.2 Mop/s.
When looking at the performance-per-Watt of the Atom 330 against the PandaBoard ES hardware, ARM is an astounding win. EP.C on the Atom 330 averaged 0.59 Mop/s per Watt where as the single PandaBoard ES was nearly three times as efficient with its 1.6 Mop/s per Watt average and the entire 12-core cluster at 1.78 Mop/s per Watt.