Friday, September 13, 2019

AMD Ryzen 3000 Boost-Clock controversy and what you need to know



If you’re an enthusiast like me, you must be aware of the ongoing controversy over the boost-clock speeds of AMD’s recently launched Ryzen 3000 series processors. What started with some early adopters finding it hard to hit the rated boost frequencies on their respective Ryzen CPUs has now found its way into more serious contention, supported by claims from both reliable and unreliable sources. Things have specially heated-up after well-known overclocker “der8auer” conducted a survey which puts a big question mark on the ability (or the lack there-off) of most 3rd gen Ryzen CPUs to operate at their advertised max boost-clock! While this controversy doesn’t necessarily jeopardize Ryzen’s status as the current champ of desktop processors on the whole, it sure creates a cloud of confusion or two in the mind of average consumer and enthusiast alike. Here we’ll try to dispel any such confusion by going deep into the matter and seek the truth.

First of all, we need to understand that this isn’t a single isolated issue; rather, a bunch of vectors are likely at work here, making things look more complicated than they actually are. Among those will be – Ryzen’s design principles, the new boost-clock algorithms, cooling and thermals, BIOS and Windows optimization and of course silicon lottery and binning. Any of these can play an important role when it comes to processor clock-speed, and, in the case of Ryzen 3000 chips, probably all of these are involved at some level or other.

Core of the matter - Zen 2, Precision Boost 2.0 and others: Back in July, when Ryzen 3000 was launched along with a flurry of gushing reviews, one thing was clear from the get go – these’re not the speed demons that many thought them to be -clock-speed wise. Coming from Ryzen 2000, there is the incremental bump of couple of hundred MHz across the range but more importantly the new Zen 2 cores (codename “Matisse”) at the heart of every Ryzen 3000 series processors don’t rely solely on blazing fast frequencies to deliver competitive performance, unlike Bulldozer/Piledriver. Instead, this time around AMD has delivered a “proper” core with a strong emphasis on IPC (Instruction per Clock-cycle) and efficiency – one that clock-for-clock can match and even surpass Intel’s best! This is a conscious design trade-off and as such AMD has made sure to extract every last MHz from TSMC’s 7nm process. Ryzen 3000 chips, specially the highend ones like Ryzen 9 3900X, Ryzen 7 3800X and Ryzen 5 3600X are clocked to their limits and have very little overclocking headroom left.

This is where Precision Boost 2.0, as AMD likes to call it, comes into play. Automatic core-clocks boosting algorithms are common place these days, both in CPUs and GPUs. The latest iteration of Precision Boost (PB) however is particularly dynamic and opportunistic. Introduced with 2nd gen ThreadRipper/Ryzen, PB can heighten the core-clocks far beyond the rated base-clock under lightly threaded (think 1 or 2 cores) workloads, provided there is thermal headroom left to do so. PB is a part of AMD’s SenseMI technology which constantly monitors hundreads of sensors employed throughout the processor silicon. It can also kick-in under heavily threaded but the boost will be significantly lower compared to when fewer number of cores are active. This is analogous to Intel’s own Turbo Boost which used to be far superior compared to AMD’s implementations, but with PB AMD has now has its answer. Let’s have look at the specs of 3rd-gen Ryzen CPUs to have a clear idea of how much Precision Boost facilitates clock rates. 



CPU
Core/Thread
Base Clock (GHz)

Boost Clock (GHz)
L3 Cache
(MB)
TDP
(Watt)
Ryzen 9 3900X
12C/24T
3.8
4.6
64
105
Ryzen 7 3800X
8C/16T
3.9
4.5
32
105
Ryzen 7 3700X
8C/16T
3.6
4.4
32
65
Ryzen 5 3600X
6C/12T
3.8
4.4
32
95
Ryzen 5 3600
6C/12T
3.6
4.2
32
65
 

As you can see, every Ryzen 3000 CPU released till date can reach significantly higher clock-speed. The Ryzen 9 3900X and Ryzen 7 3700X in particular can clock 800MHz higher than their base rating while others get a boost of 600Mhz. Needless to say that Precision Boost makes a huge difference in overall performance and efficiency, especially when it comes to your PC being more snappy and responsive. When you think that many general purpose apps and games still rely on single-thread performance, this is a big deal. 

An interesting point here is the omission of XFR (eXtended Frequency Range), -an auto-overclocking algorithm that made its debut with the original Ryzen (1st gen), carried along with the Zen+ refresh (2nd gen) and, at-least in theory could increase processor clock-speed even beyond the rated boost-clock! Instead, with Ryzen 3000 series AMD has introduced a couple of new mechanisms - Precision Boost Overdrive (PBO) and Auto Over-Clock (AOC). Off by default, these can be found both inside your motherboard BIOS and AMD’s own tuning software “Ryzen Master”. Despite the naming alikeness, these are quite different from Precision Boost, both in purpose and functionality and have more common with the MultiCore Enhancement (MCE) mechanism found in Intel motherboards. Thanks to AMD’s confusing naming and implementation, it’s very easy to mix things up!
Precision Boost 2.0 with new features
While this YouTube video should give more insights into the workings of PBO and AOC, we believe AMD should provide some clear and easy-to-understand guideline for optimizing frequency of Ryzen 3000 processors, preferably with hands-on example. But for now, let’s be clear - When people are claiming inability to hit advertised clock-speed, they are (or should be) talking about Precision Boost (PB) and not the others.

Max Boost Frequency – thermal limitation and cooling: Speaking of boost frequency, One little thing that’s very easy to miss is how Intel and AMD advertise the max boost-clock of their respective processors. On retail packages and product lists, it says “up to X.XX GHz” meaning that the chip in question is capable of reaching that speed. That however doesn’t warrant you’ll be hitting those frequencies in a plug n play manner! Boosting algorithms such PB are inherently limited by thermal constrains which means even if the conditions are right, you can’t expect to see your core-clock rise to its zenith if you don’t have sufficient cooling. Proper cooling doesn’t only help Precision Boost to kick-in it can also provide sustenance at its highest achievable frequency. Electrical (energy) limitation is a factor too but that’s more of multi-core thing and should not affect lightly threaded scenarios. You still want to invest in a motherboard with capable VRM (voltage regulator module) array to make sure that the plenty of current available to the processor to sustain a boost state for longer period of time.
The bundled Wraith Prism is a capable little cooler
So what then qualifies as proper cooling, you may ask. From what we’ve seen AMD’s own Wraith coolers are pretty impressive considering these come bundled with Ryzen CPUs. When it comes to attaining the maximum boost, a hefty 360mm all-in-one liquid cooler will definitely fare better compared to the “free” Wraith, but not by a huge a margin. Here is a test to prove that not only Wraith coolers are awesome value additions but these are enough for Precision Boost to work its magic. But there are other factors like ambient temperature, case airflow and mounting of the cooler itself which can and will impact the final outcome.

With highend models, as the number of cores and clock-speed start to scale-up, the role of your cooling set-up becomes even more crucial. This applies equally to Intel and AMD. It takes nothing short of a dual fan 280mm AIO liquid cooler for Intel’s i9 9900K to sustain its boost frequencies and even then you’ll only see it occasionally hit the advertised 5GHz!

The silicon lottery - not two CPUs are made the same: Turns out neither are two cores, at least in case of 3rd gen Ryzen! When Tom’s Hardware enquired into the matter, they found that not every core inside their retail Ryzen 5 3600X are capable of hitting the chip’s rated 4.4 GHz boost clock! It goes to show that a Ryzen 3000 Core Complex (CCX) is composed of both slower and faster cores. AMD also has confirmed it. Although the speed gap between the cores is down to a trivial ~50-75 MHz, it is there. Thankfully however, the latest versions of Windows 10 comes with a scheduler which in coaction with AMD’s Ryzen Master software can mitigate this issue by identifying and assigning threads to the fastest cores within a Core Complex (CCX). Since the highest extension of Precision Boost is only called upon when only one or two cores are active, the rest of the cores can clock down and sit back to provide additional thermal headroom.

Interesting but hardly surprising! During lunch reviews not many reviewers could get their samples, which are supposed to be cherry-picked, past 4.3GHz all core overclock -even with some very uncomfortable amount of voltages. That was the telltale sign of the fact that with Matisse AMD has well and truly hit the limits of 7nm process node. It is only with some clever binning at the silicon level that AMD could deliver those max-boost numbers. And we’re fine with that as long as the CPUs hit those frequencies.

This is also the reason why we’ll advise against manually overclocking Ryzen 3000 CPUs. Trying so will only net you few hundred MHz on all core while you’ll lose out on the ability of those faster cores to boost far beyond what the CPU is capable as a whole. Not a good trade-off!

The state of the early BIOS/AGESA and AMD’s fix: When it comes to performance optimization of newly launched platform such as Ryzen 3000, the most important aspect is perhaps the state of its own BIOS. Motherboard makers spend some of their busiest times during any new processor lunch, integrating copious amounts data in form of patches, updates and bug-fixes into their mainboard’s BIOS or AGESA (AMD Generic Encapsulated Software Architecture) as it is called within AMD platforms. An early BIOS is a work in progress with lots of fine-tuning going on with each update but it can be a great source of confusion too, specially among the early adopters who are yet to familiarise themselves to its intricacies. Have a look at the image billow to understand just how much of an impact a firmware update or revision can bring about.
Boost-clock scaling with different firmware, image credit - AnandTech
As you can see, the newer version significantly changes the boost pattern and causes the same processor to reach higher frequencies within the same workload. Likewise, an update can potentially impact the performance negatively too. Just after the launch, there were reports of some users complaining about their CPU’s high idle temperature. Believing it could be due to the “overzealous” boost algorithm that was responding to calls from background apps inside of Windows that don’t actually need the highest power-stage or the max-boost speed, AMD made a few changes to the firmware which resulted in a more relaxed boosting behaviour. But some may perceive this as a regression of shorts. Previously there have similar controversies over Ryzen specific Windows power plans as well.  
   
AMD too seems to believe that these discrepancies are stemming from a BIOS issue and has promised to resolve it with an upcoming update. In a blogpost, the company has stated that the new firmware will fix any regression in the boost behaviour and will come with further optimization for stable and efficient operation of Ryzen 3000 series processors. While it may take a few weeks for the motherboard manufacturers to implement the fix into fully-fledged BIOS, a few beta versions can be found online and have already been put to the test. The result shows that AMD’s fix works as intended. But that doesn’t mean that we recommend flashing with beta BIOS! If you happened to be an owner of 3rd gen Ryzen processor and had issues attaining the rated max boost-clock, you should wait until there is a newer and fully working version of BIOS firmware in your motherboard vendor’s website.

What it means to you: With everything said and done, this whole Ryzen 3000 clock-speed saga could very well be one of those “blown out of proportion” things! PC hardware industry has a storied history of getting too worked up with slightest of anomalies; remember the controversies surrounding Nvidia GTX 970’s V-RAM or Radeon RX 480’s PCIe power draw? Ever since the introduction, the new Ryzen CPUs have been the most sought-after by enthusiasts and as such have drawn lots of attention from press too. But at this point it seems like we’re all reading a bit too much into the matter! That’s not to say all the reports and claims of Ryzen cores not boosting to their full potential are unsubstantial. There is certainly an element of authenticity within all this otherwise it wouldn’t have garnered a response (and a fix!) from AMD. But there are much more confusion and misinterpretation than there are checked facts and in this article we tried to bring some clarity on the whole issue.
Whether you already have bought a Ryzen 3000 series desktop processor or planning to buy one, nothing has changed. Of all the metrics relevant to a modern CPU, performance is the most important one and the latest Ryzens have no shortage of that. Just make sure that you have a motherboard with good VRM arrangement, a proper and well-mounted cooling, latest chipset drivers, latest windows updates and latest BIOS. Going by the worst possible scenario, even if your chip boosts a little shy of what it’s rated for, the impact will be negligible on most use-cases. We liked the Ryzen processors for their remarkable performance, energy efficiency and value for money and while we’ll definitely keep an eye on further developments, at the moment, we don’t see any reason to change our opinion.   



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