Following weeks of questions, reviews, re-reviews and more questions from the community and the media, AMD has come out and cleared out a couple of issues. And one of those: despite what your BIOS and sensor monitors are saying, your Ryzen CPU isn’t really running that hot.
In a post on their official blog, AMD explained that their 7 series CPUs have a sensor called “T Control”. Otherwise called tCTL, it’s the primary sensor on the Ryzen series of CPUs that reports how hot everything is.
The sensor, according to AMD, takes the temperature from the interface point between the CPU die and the heatspreader. But a problem users have been noticing – including yours truly, who has been grappling with a Ryzen 7 1800X of late – is that the tCTL sensor is offset on the 1700X and 1800X CPUs, which AMD says is necessary so “all AMD Ryzen processors have a consistent fan policy”.
“Specifically, the AMD Ryzen™ 7 1700X and 1800X carry a +20°C offset between the tCTL° (reported) temperature and the actual Tj° temperature. In the short term, users of the AMD Ryzen™ 1700X and 1800X can simply subtract 20°C to determine the true junction temperature of their processor. No arithmetic is required for the Ryzen 7 1700. Long term, we expect temperature monitoring software to better understand our tCTL offsets to report the junction temperature automatically.”
The Ryzen 7 1800X I’ve been using, which is running off a Gigabyte AX370-Gaming 5 motherboard, has been reporting idle temperatures of approximately 52-60o at idle, and higher when workloads increase. The high idle temperatures were of enough concern that I emailed AMD to ask whether the samples I’d been supplied with (which I carried by hand back from San Francisco) were faulty in some way.
For reference, I’d been monitoring the CPU temperature through a variety of applications: HWMonitor Pro; a beta version of the Ryzen Master overclocking tool, which AMD supplied; the temperature monitor in the AX370’s BIOS, and HWiNFO. All four reported temperatures of 52o and beyond.
Still, it’s nice to know that things aren’t really that hot. AMD also noted that users should still use the High Performance power plan within Windows 10, and that they “do not presently believe there is an issue” with the Windows 10 scheduler that was impacting upon Ryzen’s performance.
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“Going forward, our analysis highlights that there are many applications that already make good use of the cores and threads in Ryzen, and there are other applications that can better utilise the topology and capabilities of our new CPU with some targeted optimisations,” AMD said.
They added that Ryzen’s simultaneous multi-threading should “generally see a neutral/positive benefit” from having SMT enabled, although they linked to benchmarks from Techspot that showed the Ryzen 1800X matching Intel’s 5960X and 6600K CPUs once SMT was disabled. That’s partially down to optimisations that will come down the road, and that same analysis showed that disabling SMT had no effect in certain games.
“We have already identified some simple changes that can improve a game’s understanding of the “Zen” core/cache topology, and we intend to provide a status update to the community when they are ready.”