Power Delivery Thermal Analysis
One of the most requested elements of our motherboard reviews revolves around the power delivery and its componentry. Aside from the quality of the components and its capability for overclocking to push out higher clock speeds which in turn improves performance, is the thermal capability of the cooling solutions implemented by manufacturers. While almost always fine for users running processors at default settings, the cooling capability of the VRMs isn't something that users should worry too much about, but for those looking to squeeze out extra performance from the CPU via overclocking, this puts extra pressure on the power delivery and in turn, generates extra heat. This is why more premium models often include heatsinks on its models with better cooling designs, heftier chunks of metal, and in some cases, even with water blocks.
The 14-phase power delivery operating at 4+2 on the ASUS ROG Strix B550-F Gaming Wi-Fi
The ASUS ROG Strix B550-F Gaming Wi-Fi is equipped with a fourteen phase power delivery with fourteen SiC639 50 A power stages which is split into twelve for the CPU, and two for the SoC. It is using a an ASP1106JGQW 6-phase PWM controller which is operating in a 4+2 configuration. ASUS has opted for teamed power stages with three power stages per channel for the CPU, which should, in turn, reduce the overall VRM temperatures without sacrificing on power.
Testing Methodology
Out method of testing out if the power delivery and its heatsink are effective at dissipating heat, is by running an intensely heavy CPU workload for a prolonged method of time. We apply an overclock which is deemed safe and at the maximum that the silicon on our AMD Ryzen 7 3700X processor allows. We then run the Prime95 with AVX2 enabled under a torture test for an hour at the maximum stable overclock we can which puts insane pressure on the processor. We collect our data via three different methods which include the following:
- Taking a thermal image from a birds-eye view after an hour with a Flir Pro thermal imaging camera
- Securing two probes on to the rear of the PCB, right underneath CPU VCore section of the power delivery for better parity in case the first probe reports a faulty reading
- Taking a reading of the VRM temperature from the sensor reading within the HWInfo monitoring application
The reason for using three different methods is that some sensors can read inaccurate temperatures, which can give very erratic results for users looking to gauge whether an overclock is too much pressure for the power delivery handle. With using a probe on the rear, it can also show the efficiency of the power stages and heatsinks as a wide margin between the probe and sensor temperature can show that the heatsink is dissipating heat and that the design is working, or that the internal sensor is massively wrong. To ensure our probe was accurate before testing, I binned 10 and selected the most accurate (within 1c of the actual temperature) for better parity in our testing.
For thermal image, we use a Flir One camera as it gives a good indication of where the heat is generated around the socket area, as some designs use different configurations and an evenly spread power delivery with good components will usually generate less heat. Manufacturers who use inefficient heatsinks and cheap out on power delivery components should run hotter than those who have invested. Of course, a $700 flagship motherboard is likely to outperform a cheaper $100 model under the same testing conditions, but it is still worth testing to see which vendors are doing things correctly.
Thermal Analysis Results
We measured 54.9°C on the hottest part of CPU socket area during our testing
To cool the power delivery on the Strix B550-F Gaming Wi-Fi motherboard, ASUS is using a pair of heatsinks which aren't connected with a heat pipe. This means each heatsink is cooling different parts of the heatsink without distributing the heat between each other. Running our VRM thermal test yields a very favorable result for the B550-F Gaming Wi-Fi, with a maximum temperature of 52°C on our K-type thermal probe. This is backed up with our FLIR thermal imaging camera which measured 54.9°C on the hottest part of the area around the power delivery and the CPU. This represents fantastic performance, especially for a B550 series motherboard, and shows that the ASUS power delivery very efficient and well designed.
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