The AMD 3rd Gen Ryzen Deep Dive Review: 3700X and 3900X Raising The Bar
by Andrei Frumusanu & Gavin Bonshor on July 7, 2019 9:00 AM EST** = Old results marked were performed with the original BIOS & boost behaviour as published on 7/7.
Power Consumption & Overclocking
Power consumption of the new Ryzen 3900X and 3700X are of particular interest because it’s a very key aspect of the new generation chipsets, and AMD promises some extremely large improvements thanks to the new 7nm process node as well as the optimised chiplet design.
When comparing the single-chiplet Ryzen 3700X to the previous generation Ryzen 2700X, we’re seeing quite some dramatic differences in core power consumption. In particular power consumption at each chip’s respective peak frequency is notably different: Although the new 3700X has a 100MHz higher clock speed and thus is further up the exponential power curve, it manages to showcase 32% lower absolute power than the 2700X.
We have to remember that we’re talking about overall absolute power, and not efficiency of the chip. When taking actual performance into account through the higher clock as well as Zen2’s increased performance per clock, the Performance/W figures for the new 3700X should be significantly higher than its predecessor.
What is curious about the new chip is just how closely it follows its power limitations. The new boosting algorithm on the Ryzen 3 series is a particularly “opportunistic” one that will go as high in frequencies as it can go within its constraints, no matter the amount of CPU cores.
The constraints are as follows:
- Package Power Tracking (PPT): The power threshold that is allowed to be delivered to the socket.
- This is 88W for 65W TDP processors, and 142W for 105W TDP processors.
- Thermal Design Current (TDC): The maximum amount of current delivered by the motherboard’s voltage regulators when under thermally constrained scenarios (high temperatures)
- This is 60A for 65W TDP processors, and 95A for 105W TDP processors.
- Electrical Design Current (EDC): This is the maximum amount of current at any instantaneous short period of time that can be delivered by the motherboard’s voltage regulators.
- This is 90A for 65W TDP processors, and 140A for 105W TDP processors.
Looking at the total power consumption of the new 3700X, the chip is very much seemingly hitting and maintaining the 88W PPT limitations of the default settings, and we’re measuring 90W peak consumption across the package.
When having a closer look at the new Ryzen 9 3900X, first we have to enjoy the sheer amount of cores of this processor!
Following that, we see that this CPU’s per-core peak power consumption is quite notably higher than that of the 3700X, which is not a surprise given that the chip is clocked 200MHz higher at 4.6GHz versus “just” 4.4GHz. However even at this much higher clock, the 3900X’s power consumption remains notably lower than that of the 2700X.
Scaling up in threads as well as cores, we’re seeing a similar scaling behaviour, with the large difference being that the 3900X is maintaining higher power consumption per core (and frequency) than the 3700X. Fully loading the chip we’re seeing 118W power on the CPU cores while the package power is falling in at the exact 142W that AMD describes as the PPT limit of 105W TDP processors such as the 3900X.
Another thing to note in the results between the 3700X results and the 3900X, is that un-core power on the latter is quite higher. This really shouldn’t come as a surprise as the processor has a second chiplet who will have L3 and Infinity Fabric that will use more power.
Graphing the three processors together, we see two main aspects: Again the 3900X and 3700X both consuming notably less power than the 2700X, and the 3700X’s hard limit when reaching the 88W PPT limit while the 3900X is able to scale further up till it hits the 142W limit.
Comparing the full load power characteristics of both SKUs, they end up extremely competitive in both their respective categories. The 3700X’s 90W hard-limit puts it at the very bottom of the CPUs we’ve used in our testing today, which is quite astonishing as the chip is trading blows with the 9700K and 9900K across all of our test workloads, and the latter chip’s power consumption is well over 60% above the 3700X’s.
The 3900X is also impressive given that it’s a 12-core CPU. While posting substantial performance improvements of the 12-core Threadripper counterparts, the 3900X still manages to be significantly less thermally constrained thanks to its much lower power consumption, peaking in at 142W.
The most interesting aspect of AMD’s new opportunistic power boost mechanism lies in a CPU we weren’t able to test today: the Ryzen 7 3800X. At stock behaviour, the chip’s 105W TDP should allow it to behave a lot more like the 3900X when it comes to the higher thread-count frequencies, at least until it maxes out its 8 cores on its single chiplet, which might really put it ahead of the 3700X in terms of multi-threaded performance workloads.
Overclocking: PBO & All-Core
In POV-Ray, running the 3900X at a flat 4.3GHz at 1.35V gives it a 8.2% performance boost over stock. Enabling PBO doesn’t make much difference in multi-threaded workloads for the 3900X as it’s still being limited by the 142W PPT limit.
Unfortunately we weren’t able to further investigate raising the PPT limit for this article due to time contraints as well as currently non-final firmware version for X570 motherboards from the vendors.
Turning on PBO will increase the single-threaded performance of the 3900X by a few percent, scoring just slightly higher than the stock settings. Naturally the 4.3 GHz flat overclock will regress in performance as it loses out 300MHz peak frequency compared to stock.
Finally, a Cinebench R15 MT run shows similar multi-threaded behaviour, with the 4.3GHz flat overclock achieving a 9.2% better score, whilst the PBO overclock isn’t able to further increase frequencies beyond the default power limits of the chip.
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Daeros - Monday, July 15, 2019 - link
The only mitigation for MDS is to disable Hyper-Threading. I feel like there would be a pretty significant performance penalty for this.Irata - Sunday, July 7, 2019 - link
Well, at least Ryzen 3000 CPU were tested with the latest Windows build that includes Ryzen optimizations, but tbh I find it a bit "lazy" at least to not test Intel CPU on the latest Windows release which forces security updates that *do* affect performance negatively.This may or may not have changed the final results but would be more proper.
Oxford Guy - Sunday, July 7, 2019 - link
Lazy doesn't even begin to describe it.Irata - Sunday, July 7, 2019 - link
Thing is I find this so completely unnecessary.Not criticising thereview per se, but you see AT staff going wild on Twitter over people accusing them of bias when simple things like testing both Intel and AMD systems on the same Windows version would be an easy way to protect themselves against criticism.
It the same as the budget CPU review where the Pentium Gold was recommended due to its price/ performance, but many posters pointed out that it simply was not available anywhere for even near the suggested price and AT failed to acknowledge that.
Zombieload ? Never heard of it.
This is what I mean by lazy - acknowledge these issues or at least give a logical reason why. This is much easier than being offended on Twitter. If you say why you did certain things, there is no reason to post "Because they crap over the comment sections with such vitriol; they're so incensed that we did XYZ, to the point where they're prepared to spend half an hour writing comments to that effect with the most condescending language. " which basically comes down to saying "A ton of our readers are a*holes.
Sure, PC related comment sections can be extremely toxic, but doing things as proper as possible is a good way to safeguard against such comments or at least make those complaining look like ignorant fools rather than actually encouraging this.
John_M - Sunday, July 7, 2019 - link
A good point and you made it very well and in a very civil way.Ryan Smith - Monday, July 8, 2019 - link
Thanks. I appreciate the feedback, as I know first hand it can sometimes be hard to write something useful.When AMD told us that there were important scheduler changes in 1903, Ian and I both groaned a bit. We're glad AMD is getting some much-needed attention from Microsoft with regards to thread scheduling. But we generally would avoid using such a fresh OS, after the disasters that were the 1803 and 1809 launches.
And more to the point, the timeframe for this review didn't leave us nearly enough time to redo everything on 1903. With the AMD processors arriving on Wednesday, and with all the prep work required up to that, the best we could do in the time available was run the Ryzen 3000 parts on 1903, ensuring that we tested AMD's processor with the scheduler it was meant for. I had been pushing hard to try to get at least some of the most important stuff redone on 1903, but unfortunately that just didn't work out.
Ultimately laziness definitely was not part of the reason for anything we did. Andrei and Gavin went above and beyond, giving up their weekends and family time in order to get this review done for today. As it stands, we're all beat, and the work week hasn't even started yet...
(I'll also add that AnandTech is not a centralized operation; Ian is in London, I'm on the US west coast, etc. It brings us some great benefits, but it also means that we can't easily hand off hardware to other people to ramp up testing in a crunch period.)
RSAUser - Monday, July 8, 2019 - link
But you already had the Intel processors beforehand so could have tested them on 1903 without having to wait for the Ryzen CPU? Your argument is weird.Daeros - Monday, July 15, 2019 - link
Exactly. They knew that they needed to re-test the Intel and older Ryzen chips on 1903 to have a level, relevant playing field. Knowing that it would penalize Intel disproportionately to have all the mitigations 1903 bakes in, they simply chose not to.Targon - Monday, July 8, 2019 - link
Sorry, Ryan, but test beds are not your "daily drivers". With 1903 out for more than one month, a fresh install of 1903(Windows 10 Media Creation tool comes in handy), with the latest chipset and device drivers, it should have been possible to fully re-test the Intel platform with all the latest security patches, BIOS updates, etc. The Intel platform should have been set and re-benchmarked before the samples from AMD even showed up.It would have been good to see proper RAM used, because anyone who buys DDR4-3200 RAM with the intention of gaming would go with DDR4-3200CL14 RAM, not the CL16 stuff that was used in the new Ryzen setup. The only reason I went CL16 with my Ryzen setup was because when pre-ordering Ryzen 7 in 2017, it wasn't known at the time how significant CL14 vs. CL16 RAM would be in terms of performance and stability(and even the ability to run at DDR4-3200 speeds).
If I were doing reviews, I'd have DDR4-3200 in various flavors from the various systems being used. Taking the better stuff out of another system to do a proper test would be expected.
Ratman6161 - Thursday, July 11, 2019 - link
"ho buys DDR4-3200 RAM with the intention of gaming would go with DDR4-3200CL14 RAM"Well I can tell you who. First Ill address "the intention of gaming". there are a lot of us who could care less about games and I am one of them. Second, even for those who do play games, if you need 32 GB of RAM (like I do) the difference in price on New Egg between CAS 16 and CAS 14 for a 2x16 Kit is $115 (comparing RipJaws CAS 16 Vs Trident Z CAS 14 - both G-Skill obviously). That's approaching double the price. So I sort of appreciate reviews that use the RAM I would actually buy. I'm sure gamers on a budget who either can't or don't want to spend the extra $115 or would rather put it against a better video card, the cheaper RAM is a good trade off.
Finally, there are going to be a zillion reviews of these processors over the next few days and weeks. We don't necessarily need to get every single possible configuration covered the first day :) Also, there are many other sites publishing reviews so its easy to find sites using different configurations. All in all, I don't know why people are being so harsh on this (and other) reviews. its not like I paid to read it :)