Power Consumption and Temperatures

With the test bench update, I have also overhauled my temperature measurement and methodology. For measurement, I now use a Reed SD-947 4 channel Data Logging Thermometer paired with four Omega Engineering SA1 Self Adhesive Thermocouple probes. One probe directly touches the chipset and two are placed on select power stages. The last probe actively logs the ambient temperature.


For the ASUS ROG Crosshair VIII Impact, both probes are placed near the center of the Vcore power stages. A probe is left out to log the ambient temperature. All temperatures are presented as Delta-T normalized to 20 °C, which is the measured temperature minus the ambient temperature plus 20 °C. The final result accounts for changes in ambient temperature (including those over the course of a test), while the data is presented as if the ambient were a steady 20 °C for ease of representation. Additionally, there is no longer any direct airflow over the VRM with this new setup, placing extra strain on the VRM cooling.

For the numbers seen in the chart above, I use wPrime for both temperature and power draw as it is the most intense. However, relatively short tests do not put enough strain on the system to get a look at how the VRM performs at the limit, so I added an additional test to try to thermally abuse Vcore as much as possible. It involves a 30 minute Prime95 run at the maximum overclock the motherboard can maintain, again with no airflow over the VRM. Temperatures are logged every second, and the two probes are then averaged for a cleaner presentation before subtracting the ambient to calculate the Delta-T. The results are charted below.


Between the overbuilt, highly efficiency VRM, hefty heatsink, and active cooling, I couldn't even make the ASUS ROG Crosshair VIII Impact sweat. Even the backplate improves thermal performance with thermal pads and a heatpipe. Despite the SFF design, the Impact posts some of the best VRM temperatures I have seen, which is hardly a surprise with 560 A potential current output to supply my Ryzen 5 3600X, not to mention the active cooling. The two fans were never audible throughout testing, and both fans have customizable fan curves.