The 1V BIOS setting works according to software logging, although the next batch of charts may contradict that.
These next two charts show vcore as logged by HWiNFO. It’s clear that the 1V vcore result isn’t actually performing better on either CPU, though, simply by a rough comparison of how much longer the test took to complete. In the single threaded tests, it logged boosts to 4.5GHz and beyond, but the stock results won out here with a fairly constant 4575MHz for most of the single threaded test.
On the R9 3900X, clocks were less constant, but it still reported holding higher clocks than stock with 4225MHz during the multithreaded tests. The next chart shows the same type of data, except on the R9 3900X instead. From just these numbers, it would appear that the 1V vcore results are the best, as the R5 3600 held a constant 4.2GHz throughout the three multithreaded passes as well as the long single threaded pass. This first one shows the R5 3600 on the Godlike at 1V, stock, and at -0.05v offset. We’ve also zoomed the frequency charts to a 2000MHz range in order to make the differences more obvious. These next charts are all frequency plots. There’s an unholy number of charts that could be generated with the data we’ve gathered, so we’ll be focusing on the MSI Godlike board for most of this piece, just because the graphs for it are a little easier to read.
Single-threaded scores were largely unaffected and actually decreased slightly on the Godlike board with the voltage offset, so the -.05 offset for the 3900X on the Master is the best combination we’ve tried. It’s not a huge leap, but it’s a real improvement and the same behavior was shown on the X570 Master. The most interesting part of these results, however, are the scores with a negative voltage offset: the Godlike board was stable with an offset as low as -0.1V using the 3900X, and gained 2% over the stock multithreaded score. The Master actually outperformed the Godlike board here at stock as opposed to the tests with the 3600, so the trend of Ryzen 3000-related test variance continues. The 3900X, like the 3600, performed much worse than stock with vcore set to 1V. It didn’t on the 3600, but the 3900X was a different story.
Zen 3 stock manual#
That was encouraging, because it meant we were hitting real limits rather than fooling ourselves by setting an unrealistically low manual vcore, so there was a chance it might actually help performance. Pushing an offset lower than -.05V on the X570 Master actually did cause instability and boot problems. That’s why we also tested the voltage offset, shown in this next chart. Now we’ve established the truth, which is that setting a vcore this low will in fact damage performance, even if that damage doesn’t come in a form as obvious as a typical bluescreen. One-point-zero is a ridiculously low voltage to run for Ryzen 3000 CPUs, but both boards and both CPUs allowed us to set and boot at this voltage. At stock, the Godlike performed slightly better than the Master, and the best undervolt offset we could manage didn’t significantly change either board’s score. The system boots fine and doesn’t show any signs of instability, but on both motherboards there was a very real decrease in performance. In multithreaded and single-threaded results for the R5 3600, it’s immediately obvious that applying 1V vcore tanked performance. Here’s our first two charts, we’ll just take turns putting them on the screen. That means no LLC overrides or anything like that, so the boards will behave differently based on how the manufacturers configured them. We controlled vcore in the tests that called for it, we applied XMP and custom timings and voltage to the DRAM, we maxed out fan speeds and kept ambient temperatures and cooling as constant as possible, but otherwise we used the motherboards’ auto settings. We also ran Blender and logged frequency, but the Cinebench numbers are plenty for now. We did this stock, set to 1V vcore in BIOS, and then with the best negative vcore offset we could manage, which was usually. We ran the 3600 and the 3900X each both on the Gigabyte X570 Master and the MSI X570 Godlike, running Cinebench R20 three times multithreaded and then once single threaded while logging in HWiNFO and recorded the scores. It’s up to AMD to explain why their CPUs do what they do what we’re attempting to do in this piece is replicate the behavior and see if we can find a way to undervolt effectively. Lowering vcore a lot will initiate “clock stretching,” with the result that monitoring software will report normal/higher clocks while actual performance drops. To paraphrase Reddit user Boxman90’s response post, lowering vcore a little bit without being in OC mode (locking the clocks, etc.) will cause the requested voltage per core (VID) to rise in response so that the end result is nearly the same.
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