Motherboard vendors, as a group, do not have the best relationship with honest benchmarking. For decades, board manufacturers have used various tactics to improve performance, including overclocking the FSB by a few percentage points, overriding Intel’s per-core Turbo settings to implement all-core maximum clocks when XMP was enabled, and setting Intel PL2 and Tau values far in excess of anything Intel recommends to maximize benchmark results.
Now, it seems some vendors have developed a new method of accelerating AMD CPUs — one that runs counter to AMD’s explicit guidelines and that could be shortening the lifespan of your CPU without your knowledge. HWInfo’s latest version is capable of detecting this behavior and informing you whether it’s happening.
Here’s what’s going on: AMD uses a highly sophisticated technique called Adaptive Voltage and Frequency Scaling (AVFS) to control performance and thermal characteristics across the Ryzen die. Properly calibrating and tuning values depends partly on data sent over from the motherboard VRM controller. If the motherboard sends the proper value, the Ryzen CPU will be able to properly calculate its own current draw.
What happens if the motherboard doesn’t send the proper data? What happens if the motherboard sends values that are up to 50 percent too low? The CPU would effectively misunderstand its own power configuration, bypassing safety checks intended to keep the chip performing normally.
AMD already offers overclocking support and features like PBO, but this kind of current draw increase isn’t something the end-user would even be aware of. You can have your CPU configured to use 100 percent stock AMD settings — if your motherboard UEFI is deliberately miscalibrated to misunderstand your CPU’s amperage, the chip may be allowed to draw significantly more current than it otherwise would. Over time, this could damage the CPU or shorten its effective lifespan.
According to HWInfo, the reason they added this capability is that “two of the largest motherboard manufacturers still insist on using this exploit to gain an advantage over their competitors despite being constantly asked and told not to.” The AMD motherboard I’ve spent the most time with — the MSI X570 Godlike — is actually called out as a relatively good citizen, with just a 7 percent departure from expected power readings. Other boards from unnamed vendors apparently score up to 50 percent out of spec.
HWInfo provides some specific data on how this impacts the CPU’s performance. Properly configured, their Ryzen 9 3900X ran Cinebench R20 NT at 4027MHz with a peak CPU temperature of 73 degrees and a peak power consumption of 140.964W. Configured to a value 75 percent of what it should be, the 3700X hit 4103.5MHz on average, reported power consumption of just 125W on-average (out of 142W), and a peak CPU temperature of 80C. At 150 amps (50 percent of actual), the CPU hit just 4.107GHz, with a reported power consumption of 91.5W and a 79C maximum temperature. There are limits on how high voltage is allowed to scale automatically, and the 75 percent limit happened to hit them.
Image by HWInfo
In the image above, check the “CPU Power Reporting Deviation” line. You want that to read 100 percent. Anything outside of 95 percent, 92-93 percent at the outside, and you’ve got a problem.
These sorts of problems are scarcely unique to AMD — Intel has its own problems with OEMs ignoring its guidance on PL2 and Tau settings — but it’s a real problem when it comes to telling customers what’s actually going on with CPUs, and it can lead to some motherboards looking faster than others not thanks to better engineering, but because they’re overclocking CPUs in a manner that’s invisible to the naked eye.
HWInfo notes that in order to make use of this utility, you’ll need to measure the data during stable, near-full-load conditions. They recommend using Cinebench R20 NT with HWInfo itself configured to sample every 1000ms or less. HWInfo with this feature supported can be downloaded here. AMD is not alleged to support or condone this activity in any fashion — board vendors are doing this kind of thing entirely on their own recognizance.
Now Read:
- Windows 8 Banned by World’s Top Benchmarking and Overclocking Site
- MediaTek Tried to Refute Benchmark Cheating Allegations Before They Were Even Published
- Intel Shares PL1, PL2, and Tau Values on 10th Generation CPUs
from ExtremeTechExtremeTech https://ift.tt/3cM9bO6
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