VRM Overview

The VRMs themselves are cooled by a variety of heatsinks with two thermal pads making contact between them on the front and the large backplate—important as heat can accumulate here and rarely receives much airflow. On the top side a large L-shaped heatsink cools the power stages and chokes, linked using a heatpipe to balance the thermal load across the entire heatsink. We used a trio of methods to monitor VRM temperature including the ASUS software readout, which did match our own thermal probe attached to the board's 2-pin thermal probe header, while an IR laser probe backed these results up. The first two peaked at 56°C during our stress test, while the handheld IR probe measured 52°C at the hottest visible point.


Similar Vishay SiC850A 110 A power stages are used to the board's X670E predecessor for its 18+2+2 phase VRM layout and like that board too, they are configured in teamed power stages. The same is true for the PWM controller—a DIGI+ ASP2205 is used on both boards.


Nearer the primary PCIe slot, those power stages switch to Vishay SiC629A power stages for the lower two most stages. The Vishay website claims these are 50 A, but ASUS claims they are 80 A and used on multiple X870 boards too.