System Behavior And Throttle Testing
AC Power Versus Battery Performance
Pulling the power cord on the GX60 results in a 50% performance drop from the GPU, while the CPU remains almost unchanged. Although that may seem like a huge hit (and it is), keep in mind that the GX60’s Radeon HD 7970M is still faster on battery power than Nvidia's GeForce GTX 660M on AC power in full turbo mode. Games should still be playable, for the most part, even when you're on the road.
System Throttling
Running Prime95 and MSI Kombustor at the same time places a very high load on any system, with both the CPU and GPU drawing maximum power while also generating maximum heat. In the GX60's case, this means 35 W for the APU and 100 W for the GPU. If the system is not able to pull 135 W (plus the power needed for other hardware), or is not able to get rid of over 135 W of heat, it will throttle the performance of the CPU, GPU, or both in order to stay within its thermal and electrical specifications.
In the screenshot above, the CPU is running at full load on all four cores at varying speeds, while the GPU operates at 850 MHz. The fan was set at the full-speed setting. Astoundingly, the power pack draws 170 W from the wall.
Pulling the AC power causes a substantial dip in GPU speed, though plugging the GX60 back in quickly restores full clock rates.
The APU's behavior is a little more puzzling. In the graph above, we fully loaded all of the A10-4600M’s four cores for 60 seconds. Between 20 and 30 seconds, the individual cores start dropping from their Turbo Core maximum of 2.7 GHz and begin alternating between 2.0 and 2.7 GHz, with occasional dips even lower. The APU was only running around 60 degrees Celsius. If 60 degrees is the ceiling AMD defines for this chip, then it's no wonder that MSI's cooling solution is so overbuilt. It needs to be kept as cool as possible in order to maintain its peak frequencies.
As the graph shows, as soon as the load is relaxed, the A10 immediately returns to 2.7 GHz. During this whole process, the GPU is still under full load running MSI Kombustor, leaving the APU at 50% utilization. The A10 behaves the same when the GPU isn't being used, though.
MSI's system does well enough in our throttling test. Losing AC power does not trigger any problems in gaming, aside from the observed slow-down. The GPU and APU can each draw full power without straining the cooling system or power adapter. AMD's A10 does drop out of its peak Turbo Core state fairly often, mostly when it gets too hot.