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CPU Temperature Fluctuation

I’ve been using Open Hardware Monitor to control my CPU fan. This was the only app I could find that controlled it. I have an Asus ROG Strix B450-F motherboard, AMD Ryzen 5 3600 overclocked to 4,150 MHz, and the stock AMD CPU cooler. I tried to control the fan from the motherboard, but it didn’t work. I also have two NVMe SSDs, two SATA SSDs, ODD, three 140mm case fans, and a 120mm case fan, all fans blowing inward, all housed in a Corsair 110R case.

My question is why does the temperature in the processor vary over a six-hour period when the voltage, fan speed, and room temp don’t change? Do I need a better cooler? Check out the six-hour graph I have attached, and you’ll see what I mean.

–Papa Homey

THE DOCTOR RESPONDS: Your CPU is never completely idle, so it’s unsurprising that the temperature fluctuates as the CPU load changes—even if you’ve left it to its own devices. Background processes continue to run, while even light use of your PC to browse web pages or edit a text file will have some effect. All you need to do is open Task Manager to the “Processes” tab, then click on the “CPU” tab to see the constant ebb and flow in CPU usage, which will correlate to temperature changes.

Looking closely at your graph suggests that everything appears normal— your CPU temperature tends to fluctuate between 55-70C, which is well below the “safe” figure of 80C. Improving your cooling would help reduce this figure further, and the Doc is intrigued as to why all your case fans are drawing air into the case—you should ideally have the fans at the rear drawing colder air in, while fans at the front blow the hot air out. So, if you’re not currently doing this, a simple rearrangement of your current setup should help drive those CPU temperatures down further—even when overclocked, your CPU should be around 40C while idling.