AC And Battery Testing
AC Power vs Battery clock rates
Running the synthetic GPU test FurMark, you see the graphics module pegged at 950.2 MHz (for its core) and 2,500 MT/s (for the memory). Pull the power plug to run on batteries, and the default configuration's core operates at 835 MHz, while the memory data rate holds steady at 2,500 MT/s. In essence, the card comes out of Razer's higher core clock down to 835 MHz.
Running the synthetic CPU benchmark Prime95, we see the processor briefly dip to 2.8 GHz, but then speed back up and remain at its maximum Turbo Boost setting of 2.9 GHz when the power cord gets pulled.
A fairly small 60 Wh battery that can pump out 100 W of power is amazing to me. In the real world, that means you can accidentally unplug the AC adapter and you probably wouldn't even notice. There wouldn't be any glitching or stuttering, but rather a roughly 10% frame rate reduction. Under full load, you'd deplete the battery in 35 to 45 minutes, but that'd be enough time to either get your power problem fixed or shut down gracefully, without a random disconnect mid-game.
To illustrate how the system performs in both situations, I ran 3DMark Vantage plugged into the wall, and then on battery-only. The overall synthetic gaming performance and GPU scores each fall by about 10%. Meanwhile, the CPU score only falls by around 3%. The scores reflect what we saw while monitoring the system; the GPU drops out of its "turbo" mode and everything else runs at full-speed, with no throttling.
This behavior holds true in other benchmarks as well. In 3DMark 11, the score goes from 2,598 3DMarks to 2,404. In 3DMark 06, the score goes from 15,934 to 14,523. Strangely, in 3DMark 11, the Physics subtest increases from 7,381 on AC to 7,419 on battery. In Cinebench, there is no difference either way.
Can We Force The System To Throttle?
Running Prime95 and FurMark at the same time places a very heavy load on subsystems, forcing the CPU and GPU to work generate maximum heat at their highest power levels. On the Blade, this means 35 W from the CPU and 75 W from the graphics processor. If the cooling system isn't able to dissipate all of that, you'd see throttling from one or both components to keep the machine within its thermal specs.
In the image above, the Core i7's four cores are running all-out. Also, Nvidia's GPU is running at 950 MHz. The fans blow at full-speed, and the power brick pulls 154 W from the wall. There are a couple of dips in the GPU temperature, corresponding to us pulling the machine's plug, causing the GeForce module to drop from 950 MHz to 835 MHz. Plugging the Blade back in brings the speed back up.
There is no throttling under AC power, though, and switching to the battery simply brings the GPU's clock rate down. Not many notebooks perform this well under such extreme circumstances.