Our laptop test methodology parallels what we employ in GPU reviews.
For games, we tested using Metro: Last Light's benchmark on very high & high (tessellation) settings, GTA V on very high and ultra (where applicable) with no advanced graphics, Shadow of Mordor on Ultra, and Black Ops III on High.
All FPS tests were performed three times for parity. FRAPS was used to log FPS data in 30-second increments, then that data was dissected with a spreadsheet. These tests were conducted with AC power connected.
Battery life was tested using GRID: Autosport on loop until death of the battery, at which point event viewer was used to locate kernel-power events and determine point of sleep/shutdown. A simple Time B - Time A is done to get the battery life in minutes.
As a reminder, our benchmark shows these items:
Average FPS: The time-averaged frames per second of gameplay.
1% Low FPS: The FPS displayed 1% of the time. This is a better indicator than "minimum" because it is not an outlier and is more likely to jar the user.
0.1% Low FPS: Same as above, except 0.1% of the time.
The latest nVidia drivers (372.90) were used on all systems. MSI Afterburner was used to overclock the GPU core clock and memory clock on applicable systems (the GT72 Dominator Pro G).
Note that comparing cross-platform systems is challenging. There is an inherent performance delta from the CPU change, primarily, and that's something we can control for with some careful planning. For the desktop machine, despite having Skylake processors on-hand, we opted to use an i7-4790K for its comparable clockrate to the GT72 Dominator Pro G. Turbo Boost was disabled (not available on the laptops) for more linear results. All CPUs are 4C/8T.
Thermal Test Methodology
Synthetic testing was performed using 3DMark for validation. Thermal data was logged during the 3DMark Firestrike Extreme GFX 2 test, stressing the GPU at 100% load for 24 cycles. Ambient temperature is logged actively with two thermocouples, which are averaged and subtracted from the output to create a delta temperature value (dT in *C).
We strongly believe that our thermal testing methodology is among the best on this side of the tech-media industry. We've validated our testing methodology with thermal chambers and have proven near-perfect accuracy of results.
Conducting thermal tests requires careful measurement of temperatures in the surrounding environment. We control for ambient by constantly measuring temperatures with K-Type thermocouples and infrared readers. We then produce charts using a Delta T(emperature) over Ambient value. This value subtracts the thermo-logged ambient value from the measured diode temperatures, producing a delta report of thermals. AIDA64 is used for logging thermals of silicon components, including the GPU diode. We additionally log core utilization and frequencies to ensure all components are firing as expected. Voltage levels are measured in addition to fan speeds, frequencies, and thermals. GPU-Z is deployed for redundancy and validation against AIDA64.
All open bench fans are configured to their maximum speed and connected straight to the PSU. This ensures minimal variance when testing, as automatically controlled fan speeds will reduce reliability of benchmarking. The CPU fan is set to use a custom fan curve that was devised in-house after a series of testing. We use a custom-built open air bench that mounts the CPU radiator out of the way of the airflow channels influencing the GPU, so the CPU heat is dumped where it will have no measurable impact on GPU temperatures.
We use an AMPROBE multi-diode thermocouple reader to log ambient actively. This ambient measurement is used to monitor fluctuations and is subtracted from absolute GPU diode readings to produce a delta value. For these tests, we configured the thermocouple reader's logging interval to 1s, matching the logging interval of GPU-Z and AIDA64. Data is calculated using a custom, in-house spreadsheet and software solution.
Endurance tests are conducted for new architectures or devices of particular interest, like the GTX 1080, R9 Fury X, or GTX 980 Ti Hybrid from EVGA. These endurance tests report temperature versus frequency (sometimes versus FPS), providing a look at how cards interact in real-world gaming scenarios over extended periods of time. Because benchmarks do not inherently burn-in a card for a reasonable play period, we use this test method as a net to isolate and discover issues of thermal throttling or frequency tolerance to temperature.
Our test starts with a two-minute idle period to gauge non-gaming performance. A script automatically triggers the beginning of a GPU-intensive benchmark running MSI Kombustor – Titan Lakes for 1080s. Because we use an in-house script, we are able to perfectly execute and align our tests between passes.
Noise Testing Methodology
Our noise testing methodology is new and still being revised, but has been kept consistent across all tests contained herein. We test noise in a real-world environment and do not presently use an anechoic chamber. The results align with what consumers will encounter in their own rooms.
We use a REED logging dB meter mounted to a tripod, whose mic is positioned 20” from the face of the GPU (mounted in an open bench). The REED meter is approximately 6” above the bench. All open bench fans are disabled. The Kraken X41 CPU cooling fan is configured to its “silent” mode, minimizing its noise output to be effectively imperceptible.
A noise floor measurement is taken prior to each test's execution to determine ambient without any systems running in the room. We then take an idle measurement (GPU & CPU at idle). Our noise floor has a fluctuation of approximately +/-0.6dB.
Noise levels are logarithmic, and are therefore not as simple to perform delta calculations as thermals or framerates. Noise percent differences are calculated using dB=20*log(V2/V1) (where V is amplitude). You cannot perform a simple percent difference calculation to determine the delta. For an example, a 10dB range (50dB vs. 40dB) is not equal to a 22% delta.
After the noise floor is determined, we log idle fan dB, 50% speed dB, and 100% speed dB (configured in Afterburner). We also measure auto fan dB at an identical stepping for every test; we do this by running Kombustor for exactly 5 minutes prior to beginning dB logging, which is useful for fans which use two push fans. Some dual-push fan cards will only trigger the second fan if the VRM is under load.