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AMD's Ryzen 3000 processors have drastically improved single-threaded performance, but you'll lose that benefit if you choose to overclock the Ryzen 3000-series processors manually. This unfortunate side effect comes because the chips can't be manually overclocked on all cores to reach the same frequency as the single-core boost frequency. In fact, we often find the all-core overclock ceiling to be 200 to 300 MHz lower than the rated boost speeds (which we did see activate frequently on our Ryzen 5 3600X sample).

We've tested several of the Ryzen 7 processors and the Ryzen 9 3900X in manually-overclocked configurations throughout our entire suite of benchmarks, and the results are predictable: You gain some extra threaded performance over automatic overclocking with PBO, but lose too much performance in lightly-threaded apps to make it worthwhile. In other words, outside of a few edge cases, like systems that will only do heavily-threaded work, manual overclocking simply isn't worth your time -- or the egregious power consumption it requires for relatively small performance gains.

So we're sticking with AMD's PBO feature for this round of testing. As we've seen, these algorithms provide a speedup that improves threaded performance while also leaving the single-core boost frequency intact. The feature also keeps the Ryzen processor in its power-to-performance sweet spot, which means that it doesn't require too much additional power consumption or cooling. Unfortunately, the gains via PBO are slight, so you definitely shouldn't expect miracles, but they are worthwhile if you have sufficient cooling. However, given the relatively small performance boosts, we think you could get most of the PBO feature with the stock cooler, which we'll put to the test today.

AMD's Precision Boost Overdrive (PBO) is an adaptive overclocking approach that allows the processor to communicate with the platform to modulate performance based on the motherboard's power delivery subsystem and thermal dissipation capabilities. The processor monitors Package Power Tracking (PPT), which is total socket power, and the Thermal Design Current (TDC) variable, which is the motherboard's maximum available sustained current. Electrical Design Current (EDC) also indicates the maximum current possible from the VRMs during peak/transient conditions.

AMD enables two options for PBO: IPM is AMD's default PBO setting, which is activated if you leave the PBO setting to 'Auto' in the Godlike's UEFI. But you can select 'Enabled' to activate a profile that's dictated by the maximum limits of the motherboard's power delivery subsystem. These limits vary by motherboard and are defined by the vendor. We chose the latter to unlock the full potential of PBO. This setting kicks the socket's maximum power delivery up to 1000W to offer the best of increased multi-core boost clocks while retaining the high single-core boost clocks.

You can also further tune the power delivery options with an Auto OC (AOC) feature. This new feature grants you some control over the maximum attainable boost clocks by allowing you to add up to an extra 200MHz to the maximum boost clock, but it isn't guaranteed that the processor will reach those speeds at all times, or under all conditions. Instead, the processor will still respect the limits imposed by the motherboard maker.

Unfortunately, we've found that the PBO+AOC feature often comes at the expense of performance in single-threaded workloads even though it is billed as retaining, and even heightening, single-core boost clocks. From a performance and power consumption standpoint, it is more comparable to an all-core overclock. We chose to go with the limits of the motherboard, noted on the charts as PBO.

The new AMD-optimized Windows scheduler is only present in Windows 10 1903 and promises to expose gains in several types of applications. As such, we updated our test image to the latest version of Windows 10 available (18362.207). All of our test results come from the aforementioned operating system and include all publicly available security mitigations and the latest motherboard firmware revisions. Intel is currently impacted by Spectre, Spectre v4, Meltdown, Foreshadow, Spectre v3a, Lazy FPU, Spoiler, and MDS, while AMD is only impacted by Spectre and Spectre v4. AMD has added hardware-based mitigations for both variants of Spectre, which should reduce the performance impact, but the requisite patches for both companies have performance penalties, which are reflected here in our testing.

Intel's motherboard partners have infused their boards with predefined all-core boost profiles that go by many names, such as Multi-Core Enhancement (MCE) with ASUS motherboards and Enhanced Turbo with our MSI motherboard. These features are largely referred to as MCE, but the functionality remains the same: These settings essentially apply an all-core overclock to the processor that is defined by the maximum Turbo Boost bin supported by the processor. This setting modifies the CPU's clock rate and voltage to deliver higher performance, which is basically factory-sanctioned overclocking.

MSI turns this on by default in its BIOS, similar to most of its competition. Performance, power consumption, and heat are all affected, naturally. We manually disable this feature for our stock CPU testing to best reflect Intel's specifications. 

We added in several new tests from Phornix's open-source benchmark suite. While this suite is heavily focused on Linux test environments, the benchmark utility does have several powerful testing options for Windows systems, along with Apple OS X, GNU Hurd, Solaris, and BSD operating systems. The test also outputs deviation metrics that help ensure accuracy in our test results.

We're integrating key tests, like GIMP productivity, web browser benchmarks, SVT-AV1 encoding, NAMD, and a build-llvm compile-time test.

We're using MSI's MEG X570 Godlike as our test platform for the second- and third-gen AMD processors. Due to the compatibility matrix for the AM4 socket, we stepped back to the MSI X470 Gaming M7 AC for the Ryzen 7 1800X.

The pricey Godlike board retails for around $800, but has the 14+4+1-phase power delivery subsystem to support aggressive overclocking.

The MEG X570 Godlike sits at the top of MSI's X570 motherboard hierarchy. It also comes with a few nifty accessories like a 10Gb “Super LAN” Ethernet card and a PCIe Gen 4 Xpander-Z M.2 expansion card. That lets you add two more M.2 drives to complement the three M.2 PCIe Gen 4 M.2 ports on the board. You also get four PCIe 4.0 x16 slots, an RGB Mystic Light Infinity II mirror over the IO shroud, and a tiny OLED screen, alongside the two-digit LCD display for error codes.

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Paul Alcorn is the Managing Editor: News and Emerging Tech for Tom's Hardware US. He also writes news and reviews on CPUs, storage, and enterprise hardware.

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