提高AMD Ryzen(AMD Ryzen)处理器性能的功能之一是Precision Boost，它可以在工作负载增加时提高处理器内核的频率，同时控制能耗(energy consumption)和温度。如果您查看主板的BIOS，您还可以看到其他术语，例如PBO（Precision Boost Overdrive）和 AutoOC（Auto OverClocking）。您可能会对它们的含义、它们的作用以及它们是否能真正提高您获得的性能感到困惑。为了检查PBO 和 AutoOC(PBO and AutoOC)是否确实有所作为，我们决定在AMD Ryzen 7上对其进行测试(AMD Ryzen 7)3700X 处理器。继续阅读并了解这些功能对您获得的整体性能的影响：
AMD的PBO（Precision Boost Overdrive）和AutoOC（自动超频(Auto OverClocking)）是什么？
第三代锐龙处理器同时提供PBO 和(PBO and AutoOC)AutoOC(Ryzen)。PBO来自Precision Boost Overdrive ，如果主板的(Precision Boost Overdrive)电压调节器模块(Voltage Regulator Modules)( VRM ) 可以处理它们，并且处理器的温度不会太高，则 PBO可以让您的AMD 第 3(AMD 3rd)代 Ryzen 处理器(Gen Ryzen processor)长时间保持较高的电压。Precision Boost Overdrive与Precision Boost不同，后者已经处理了处理器的库存升压时钟(stock boost clock)。PBO 意味着更多的电力通过您的Ryzen 处理器(Ryzen processor) ，但前提是它可以处理它。PBO 的一个结果是，如果我们提到的功率和热条件都得到满足，它可能允许更高的 CPU 升压时钟。(A consequence of PBO is that it might allow for higher CPU boost clocks if the power and thermal conditions that we mentioned are all met.)
AutoOC或Auto OverClocking是处理器加速行为(boost behaviour)的偏移量，您可以将其设置为最多比CPU的默认(CPU)最大加速(maximum boost)时钟高 200 MHz。因此(Thus)，AutoOC让AMD Ryzen处理器自动超过其最大升压(maximum boost)时钟。如果不超过允许的最大电压，AutoOC 应该能够提升锐龙处理器的单核性能(AutoOC should be able to increase the single-core performance of a Ryzen processor)。此外，虽然它不是PBO的一部分，但AutoOC可以与它结合使用以允许更高的为您的处理器提升时钟(boost clock)。然而，启用它并不意味着处理器真正达到了比其制造商指定的更高的升压时钟。(boost clock)理论上，它允许处理器做到这一点，前提是电压和热限制没有超过。
在AMD Ryzen 7 3700X 处理器上启用PBO 和 AutoOC(PBO and AutoOC)
Ryzen 7 3700X是一款快速处理器，配备 8 个物理内核和 16 个线程。它以3600 MHz的标准(MHz)频率(stock frequency)运行，最高可提升至 4.4 GHz。AMD使用公司新的Zen 2 CPU 架构(CPU architecture)在 7 纳米制造工艺(manufacturing process)上构建了Ryzen 7 3700X 。它不仅速度快，而且还具有仅为 65瓦的低(Watts)TDP。
因为我们想看看打开PBO 和 AutoOC(PBO and AutoOC)是否会对我们的AMD Ryzen 7 3700X 产生影响，所以我们决定运行一些基准测试。但首先，这是我们测试它的硬件平台：(hardware platform)
- 主板：华硕ROG Crosshair VIII Hero(ASUS ROG Crosshair VIII Hero)（Wi-Fi）
- 冷却器：ROG Ryou 120
- 内存：HyperX Predator DDR4 RGB 内存(HyperX Predator DDR4 RGB Memory)（2 x 8GB，3600MHz）
- 显卡：华硕 ROG STRIX (Card)GTX 1660 (ASUS ROG STRIX GTX 1660) Ti GAMING OC
- 存储：ADATA XPG Gammix S11 Pro SSD
- 显示器：华硕 ROG Strix XG32VQ( ASUS ROG Strix XG32VQ)曲面电竞显示器(Gaming Monitor)（32 英寸WQHD 2560 x(x 1440) 1440，144Hz）
- 电源(Power Supply Unit)：ASUS ROG Thor 850W Platinum
- 操作系统(Operating System)：Windows 10 Pro x64，2019年 5 月(May 2019) 更新(Update)
我们的ASUS ROG Crosshair VIII Hero ( Wi-Fi ) 主板基于X570 芯片组(X570 chipset)并提供出色的UEFI BIOS。我们感兴趣的设置可在其Extreme Tweaker页面上找到，您可以在其中启用“Precision Boost Overdrive”，并将AutoOC Offset 值(AutoOC Offset value)（在我们的主板上，称为“Max CPU Boost Clock Override”）设置为最大 200兆赫(MHz)。从理论上讲(Theoretically)，这意味着处理器可以将其升压时钟(boost clock)从现有的4.4 (stock 4.4) GHz超频到 4.6 GHz。
为了查看处理器性能(processor performance)是更好还是更差，我们运行了 3 次相同的基准测试：一次是CPU(CPU running)以库存设置运行，一次是启用PBO ，一次是启用(PBO)PBO并且AutoOC设置为偏移 200 MHz。
所有基准测试均在Windows 10 Pro版本 1903(version 1903)内部版本 18362.418 和可用的最新驱动程序上运行。
让我们看看我们在游戏和基准测试中的结果，同时在股票设置上运行我们的AMD Ryzen 7 3700X，启用PBO，以及设置为使用PBO & AutoOC +200 MHz时：
PBO 和 AutoOC 是否(PBO and AutoOC)给您带来了性能提升(performance boost)？
我们运行的第一个基准测试是CPU-Z中的基准测试。Single-Thread分析处理器的单核性能，在开启“Precision Boost Overdrive”和启用PBO + AutoOC时，速度都有小幅提升。但是，速度只增加了一点点：PBO 为 0.39%，PBO和 AutoOC(PBO and AutoOC)为 1.37% 。这些是测试可变性区域(variability zone)内的分数，因此我们认为它们不是决定性的。
在测试多核性能的CPU-Z Multi-Thread中，为AMD Ryzen 7 3700X 设置(AMD Ryzen 7)“Precision Boost Overdrive”似乎提供了微小的性能提升(performance improvement)，与在库存设置下运行CPU相比（提高了 0.84%） )，并打开AutoOC（好 0.77%）。尽管看起来很奇怪，但这些结果也在测试变异范围(variability margin)内。
在Cinebench R20中，它在渲染图像时评估处理器的速度，启用PBO会导致 1.78 % improvement，并且打开AutoOC 会(AutoOC)导致比库存设置% improvement尽管数量不多，但我们可以说在出厂默认设置下运行处理器会带来一点小小的提升。
在另一个渲染基准Blender中，当我们启用(Blender)“Precision Boost Overdrive”时， ("Precision Boost Overdrive")AMD Ryzen 7 3700X 的表现略好，但当我们也打开自动超频时，它比运行股票差。
PCMark 10告诉我们处理器在日常计算任务中的能力，例如网页浏览(web browsing)、视频会议(video conferencing)、应用程序启动时间、生产力和数字内容创建(content creation)。在这个基准测试中，3700X 在默认设置下运行的得分比启用“Precision Boost Overdrive”和 PBO + AutoOC 时的得分更高。
奇怪的是，在7-Zip的压缩测试中，与在默认设置下运行处理器或启用(compression test)“Precision Boost Overdrive”和 AutoOC时相比，打开PBO意味着速度略低 (4%) 。
在减压测试(decompression test)中，我们看到了同样的情况：仅启用PBO意味着性能略有下降。启用PBO后，锐龙(PBO)7(Ryzen 7) 3700X比在出厂设置下运行时慢 0.30%，比同时开启AutoOC时慢 1.11% 。同时启用“Precision Boost Overdrive”和AutoOC，处理器比没有打开它们时快 0.50%。
在JetStream 2中，我们在(JetStream 2)Google Chrome中运行的网络浏览器基准测试(web browser benchmark)，启用PBO and PBO + AutoOC意味着同样的事情：性能小幅提升 1.35 % increase。
对于游戏玩家，我们还测试了几款游戏：《古墓丽影(Tomb Raider)》、《地铁离去(Metro Exodus)》和《僵尸世界大战》(World War Z)。我们将它们设置为以 1920 x 1080像素的分辨率和可用的最低图形细节运行，这样我们的显卡就不会成为Ryzen 7 3700X 的瓶颈。
在《古墓丽影(Tomb Raider)之影(Shadow)》中，CPU 渲染测量(CPU Render measurement)显示，无论启用PBO or PBO + AutoOC都没有任何好处。在没有“Precision Boost Overdrive”("Precision Boost Overdrive")和自动超频的情况下，我们每秒获得了更多的帧数。
在Metro Exodus中，无论我们如何配置(Metro Exodus)AMD Ryzen 7 3700X，每秒的帧数几乎相同，尽管启用“Precision Boost Overdrive”意味着少一帧。
World War Z是唯一一款在开启PBO（多 3 帧）和启用AutoOC（多 8 帧）时性能更好的游戏。
为了了解启用“Precision Boost Overdrive ”对处理器温度的影响程度，我们在运行Prime95时使用(Prime95)HWiNFO进行了一些记录。在出厂设置下运行时，处理器的温度没有超过 89摄氏度(Celsius)。但是，在启用PBO and PBO + AutoOC的情况下，处理器达到了 95摄氏度(Celsius)，这是它的最高官方温度。
正如预期的那样，启用PBO 和 AutoOC(PBO and AutoOC)也意味着更高的功耗(power consumption)。我们的处理器从出厂设置时的 90瓦增加到打开(Watts)“Precision Boost Overdrive”时的 100("Precision Boost Overdrive")瓦(Watts)，并在启用AutoOC时达到 117瓦(Watts)。
我们还记录了单个内核的最大提升频率。(boost frequency)我们的发现非常令人惊讶：当使用其原始设置运行时， Ryzen 7 3700X 在单核上达到了 4392 MHz，这非常接近其宣传的 4.4 GHz最大升压时钟(boost clock)。但是，当我们启用“Precision Boost Overdrive ”时，最大提升频率(boost frequency)更低，为 4367 MHz，而当同时开启AutoOC时，它甚至更低，为 4342 MHz。这绝对不是我们所期望的。
结论：没有理由使用Precision Boost Overdrive 和 AutoOC(Precision Boost Overdrive and AutoOC)
我们的结论是，如果您使用的是AMD Ryzen 7 3700X， (AMD Ryzen 7)“Precision Boost Overdrive”和PBO + AutoOC都不值得启用：
- 基准测试中的性能提升好坏参半。尽管您可以获得百分之一的速度提升(percent speed boost)，但通常情况下，您的性能会降低
- 在某些游戏中，您每秒获得的帧数多一些，但在其他游戏中，您每秒获得的帧数更少
- 由于使用了更高的电压，处理器的温度和功耗都会增加(power consumption increase)
因此，我们的结果好坏参半，我们决定关闭“Precision Boost Overdrive”的("Precision Boost Overdrive")AMD Ryzen 7 3700X ，因为我们认为启用它并没有真正的好处。在我们看来，至少在这一点上，PBO 和 AutoOC(PBO and AutoOC)弊大于利。这里没有实际的性能提升(performance gain)，只是更高的温度和功耗(power consumption)，在我们看来，这只会导致处理器寿命缩短和电费(electricity bill)增加。但是，随着AMD发布新的AGESA 固件(AGESA firmware)，以及主板制造商也发布新的BIOS ，未来情况可能会发生变化。(BIOSes)我们将不得不拭目以待。
Does AMD's PBO (Precision Boost Overdrive), and AutoOC (Auto OverClocking) increase performance?
One of the features that increases the performance of AMD Ryzen processors is Precision Boost, which raises the frequency of the processor's cores when the workload increases, while keeping both the energy consumption and the temperature in check. If you look into the BIOS of your motherboard, you can also see other terms like PBO (Precision Boost Overdrive) and AutoOC (Auto OverClocking). You may be confused by what they mean, what they do, and whether they can truly enhance the performance you get. To check whether PBO and AutoOC do make a difference, we decided to test them on an AMD Ryzen 7 3700X processor. Read on and see the impact of these features on the overall performance you get:
What are AMD's PBO (Precision Boost Overdrive), and AutoOC (Auto OverClocking)?
The 3rd generation Ryzen processors offer both PBO and AutoOC. PBO comes from Precision Boost Overdrive and enables your AMD 3rd Gen Ryzen processor to maintain higher voltages for longer times, if the motherboard's Voltage Regulator Modules (VRM) can handle them, and if the temperature of the processor does not get too high. Precision Boost Overdrive is not the same thing as Precision Boost, which already handles the stock boost clock of the processor. PBO means more electrical power going through your Ryzen processor, but only if it can handle it. A consequence of PBO is that it might allow for higher CPU boost clocks if the power and thermal conditions that we mentioned are all met.
AutoOC or Auto OverClocking is an offset for the processor's boost behaviour, which you can set at a maximum of up to 200 MHz more than the default maximum boost clock of the CPU. Thus, AutoOC lets AMD Ryzen processors automatically push past their maximum boost clocks. If the maximum voltage allowed is not exceeded, AutoOC should be able to increase the single-core performance of a Ryzen processor. Furthermore, although it is not part of PBO, AutoOC can be used in conjunction with it to allow higher boost clocks for your processor. However, enabling it does not mean that the processor truly reaches a higher boost clock than the one specified by its manufacturer. In theory, it allows the processor to do that, only if voltages and thermal limits are not overstepped.
Enabling PBO and AutoOC on an AMD Ryzen 7 3700X processor
The Ryzen 7 3700X is a fast processor that comes with 8 physical cores and 16 threads. It runs at a stock frequency of 3600 MHz and can boost up to 4.4 GHz. AMD built the Ryzen 7 3700X using the company's new Zen 2 CPU architecture, on a 7-nanometer manufacturing process. It's not just fast, but it also comes with a low TDP of just 65 Watts.
Because we wanted to see whether turning PBO and AutoOC on would make a difference on our AMD Ryzen 7 3700X, we decided to run some benchmarks. But first, here is the hardware platform on which we tested it:
Our ASUS ROG Crosshair VIII Hero (Wi-Fi) motherboard is based on the X570 chipset and offers an excellent UEFI BIOS. The settings that we were interested in are available on its Extreme Tweaker page, where you can enable "Precision Boost Overdrive", as well as set the AutoOC Offset value (on our motherboard, it's called "Max CPU Boost Clock Override") to a maximum of 200 MHz. Theoretically, that means that the processor is allowed to overclock its boost clock from stock 4.4 GHz up to 4.6 GHz.
To see whether the processor performance is better or worse, we ran the same benchmarks three times: once with the CPU running at stock settings, once with PBO enabled, and once with PBO enabled and AutoOC set at an offset of plus 200 MHz.
All the benchmarks were run on Windows 10 Pro, version 1903, build 18362.418, and the latest drivers available.
Let's see what results we have had in games and benchmarks, while running our AMD Ryzen 7 3700X on stock settings, with PBO enabled, and when set to use PBO & AutoOC +200 MHz:
Do PBO and AutoOC give you a performance boost?
The first benchmark that we ran was the one in CPU-Z. The Single-Thread, which analyzes the single-core performance of the processor, showed a small improvement in speed both when turning "Precision Boost Overdrive" on and when enabling PBO + AutoOC. However, the speed increased only by a little: 0.39% with PBO, and 1.37% with PBO and AutoOC. These are scores within the testing variability zone, so we do not find them conclusive.
In CPU-Z Multi-Thread, which tests the multi-core performance, setting "Precision Boost Overdrive" on for the AMD Ryzen 7 3700X seemed to offer a tiny performance improvement, compared to both running the CPU at stock settings (0.84% better), and turning on AutoOC (0.77% better). Although it looks odd, these results are also within the testing variability margin.
In Cinebench R20, which evaluates the processor's speed when rendering images, enabling PBO resulted in a 1.78% improvement, and turning AutoOC on resulted in a 2.20% improvement over stock settings. Although it is not much, we can say that there is a small boost from running the processor at its factory defaults.
In Blender, another rendering benchmark, the AMD Ryzen 7 3700X performed marginally better when we enabled "Precision Boost Overdrive", but when we also turned on auto-overclocking, it was worse than running stock.
PCMark 10 tells us how capable a processor is in daily computing tasks, such as web browsing, video conferencing, apps start-up times, productivity, and digital content creation. In this benchmark, the 3700X got a better score when running at default settings than it did when "Precision Boost Overdrive" and PBO + AutoOC were enabled.
Oddly, in 7-Zip's compression test, turning PBO on meant slightly less speed (4%) than when running the processor at default settings or when enabling "Precision Boost Overdrive" and AutoOC.
In the decompression test, we saw the same thing: enabling just the PBO meant a small decrease in performance. With PBO enabled, the Ryzen 7 3700X was 0.30% slower than when running at factory settings, and 1.11% slower than when also turning AutoOC on. Enabling both "Precision Boost Overdrive" and AutoOC, the processor was 0.50% faster than without them turned on.
In JetStream 2, a web browser benchmark that we ran in Google Chrome, enabling PBO and PBO + AutoOC meant the same thing: a small 1.35% increase in performance.
For gamers, we also tested a few games: Shadow of the Tomb Raider, Metro Exodus, and World War Z. We set them to run at a resolution of 1920 x 1080 pixels and with the lowest graphics details available, so that our graphics card did not bottleneck the Ryzen 7 3700X.
In Shadow of the Tomb Raider, the CPU Render measurement showed that neither enabling PBO or PBO + AutoOC, had any benefits. We got more frames per second without "Precision Boost Overdrive" and auto-overclocking.
In Metro Exodus, the number of frames per second was almost the same regardless of how we configured the AMD Ryzen 7 3700X, although enabling 'Precision Boost Overdrive" meant one frame less.
World War Z was the only game in which we saw better performance when turning PBO on (3 frames more), as well as when enabling AutoOC (8 frames more).
To get an idea of how much the temperature of the processor is affected by enabling "Precision Boost Overdrive," we did some logging using HWiNFO while running Prime95. While running at factory settings, the processor did not get hotter than 89 degrees Celsius. However, with PBO and PBO + AutoOC enabled, the processor reached 95 degrees Celsius, which is its maximum official temperature.
As expected, enabling PBO and AutoOC also means higher power consumption. Our processor went from 90 Watts at factory settings, to 100 Watts with "Precision Boost Overdrive" turned on, and up to 117 Watts when AutoOC was also enabled.
We also logged the maximum boost frequency on a single core. What we found was quite surprising: the Ryzen 7 3700X reached 4392 MHz on a single core when running with its stock settings, which is very close to its advertised 4.4 GHz maximum boost clock. However, when we enabled "Precision Boost Overdrive," the maximum boost frequency was lower at 4367 MHz, and when also turning AutoOC on, it was even lower, at 4342 MHz. It is definitely not what we expected.
Conclusion: There is no reason to use Precision Boost Overdrive and AutoOC
Our conclusion is that neither "Precision Boost Overdrive" nor PBO + AutoOC are worth enabling if you are using an AMD Ryzen 7 3700X:
- The performance gains in benchmarks are mixed. Although you can get a one percent speed boost, more often than not, you're getting less performance
- In some games you get a few more frames per second, but in others you get fewer frames per second
- Both the processor's temperature and its power consumption increase, because of the higher voltages used
Hence our mixed results, we decided to keep our AMD Ryzen 7 3700X with "Precision Boost Overdrive" off, as we see no real benefit from enabling it. In our opinion, and at least at this point, PBO and AutoOC do more harm than good. There is no real-life performance gain to see here, just higher temperatures and power consumption, which in our minds translates only to a decreased longevity for the processor and a higher electricity bill. However, things might change in the future, as AMD releases new AGESA firmware, and new BIOSes are also released by motherboard manufacturers. We'll have to wait and see.
