Power Consumption and Temperatures

With the test bench update, I have also overhauled my temperature measurement 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 ASRock Z490 Phantom Gaming ITX/TB3, one probe is centered along each bank of 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 end result accounts for variation in ambient temperature (including changes over the course of a test) while presenting the data as if the ambient were a steady 20 °C for easy presentation. 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. 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.

This test typically involves a 30 minute Prime95 run at the maximum overclock the motherboard can maintain, again with no airflow over the VRM. For Z490, I took a slightly different approach. The goal was to keep VRM testing as fair as possible, so I chose to keep the stock 4.9 GHz frequency and simply boosted the voltage to 1.38 V in order to get the desired power output of around 250 W. The 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.


The ASRock Z490 Phantom Gaming ITX/TB3 did well in my VRM torture test, and the fans stayed quiet throughout the test.

Still, in the interest of those who want totally silent systems, I re-ran the test with the fans completely disabled. Obviously, temperatures were a little higher, approaching 90 °C. Given how quiet the fans are with the stock curve, I would recommend leaving them on.