OpenArena 0.8.8 at 1680 x 1050 is slightly faster than the A8-3870K in terms of performance-per-Watt. Ivy Bridge graphics on Linux for this OpenGL game is delivering the best performance-per-Watt and is a 30% improvement over Sandy Bridge HD 3000 and a 37% improvement over the slower HD 2000 graphics.
The i7-3770K system was pulling 77 Watts while the system was pulling through 71 Watts during this test when the i5-2500K was installed and 69 Watts with the i5-2400S. With the A8-3870K being locked to a lower frequency by default with the open-source Radeon stack, it was going through 60 Watts. The A8-3870K when using Catalyst was actually more power-hungry for OpenArena than even the i7-3770K with an AC power draw of 83 Watts. Now to translate that to performance-per-Watt, that is done automatically via the Phoronix Test Suite:
In terms of the CPU temperature during this process, with all of the Intel CPUs using a reference Intel HSF, the Ivy Bridge processor was only slightly warmer. The average CPU temperature with the stock heatsink was 45°C while running this game and with the Sandy Bridge CPUs it was at around 41°C.