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AMD Ryzen 9 3900X Review

AMD's new processor is seriously powerful and beats the equivalent Intel CPU in a number of areas – but can it surpass the i9-9900K when it comes to gaming?


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The AMD Ryzen 9 3900X is one of the best processors available for demanding creative tasks, thanks to super-high multi-core performance. It’s a versatile chip, too, with gaming performance proving to be solid. However, the Intel Core i9-9900K still holds the advantage here if you’re looking for a CPU for a dedicated gaming PC.


  • Top-class multi-core performance for creative tasks
  • PCIe Gen 4 support for faster SSD speeds
  • Solid gaming performance


  • Intel still has the edge for gaming

Key Specifications

  • Review Price: £529.99
  • 12 cores, 24 threads
  • 3.80GHz base clock
  • 4.6GHz boost clock
  • 7nm manufacturing process
  • PCIe Gen 4 support

What is the AMD Ryzen 9 3900X?

The AMD Ryzen 9 3900X is a member of the new Ryzen 3000-series CPUs, as AMD looks to close the gap between itself and Intel. While AMD has previously been renowned for targeting the mid-range and low-range market, its new CPU looks to challenge Intel’s latest and greatest consumer chip: the Intel Core i9-9900K

With 12 cores, 24 threads and a base clock speed of 3.8GHz, the AMD Ryzen 9 3900X is one of the most powerful Ryzen processors around, with only the AMD Ryzen 9 3950X beating it for specs.

It’s also among the very first desktop chips to be released built using a 7-nanometer process, which is a huge accomplishment since Intel’s 9th-gen alternatives are still stuck at 14 nanometers. 

But what about real-time performance? We’ve tested the AMD Ryzen 9 3900X with various benchmarks and games to see how well it stands up next to the Intel Core i9-9900K. 

Related: Best gaming CPU

AMD Ryzen 9 3900X specs – Packed with cores

The AMD Ryzen 9 3900X is part of AMD’s family of 3rd-generation processors, all built on the new Zen 2 architecture that uses one of the smallest manufacturing process in the consumer market yet at 7 nanometres.  

This marks a significant advantage over Intel, which is still struggling to reduce the size of its 14-nanometre architecture. Note that this may change with the imminent arrival of the 10th-generation Intel Core processors. 

Cores Threads Base clock speeds (GHz) Boosted clock speeds (GHz) TDP (W) Price
AMD Ryzen 9 3900X 12 24 3.8 4.6 105 £519.98
AMD Ryzen 7 3700X 8 16 3.6 4.4 65 £320
Intel Core i9-9900K 8 16 3.6 5.0 95 £475.49
Intel Core i7-8700K 6 12 3.7 4.7 95 £341.94

The main benefit of the new Zen 2 architecture is the 15% increase for instructions per cycle compared to the previous generation, improving the efficiency of the CPU’s core. Other improvements the Zen 2 architecture brings to the table include a larger cache size and a redesigned floating point engine. 

The new AMD X570 chipset also supports PCIe Gen 4. This sees a significant improvement to performance over the latest and greatest SSDs, for faster read and write speeds. As such, you’ll be able to save and load data stored on your system at a rapid rate, which will obviously be handy for both professional creatives and gamers.

Related: Intel vs AMD

AMD Ryzen 9 3900 X

The AMD Ryzen 9 3900 X is one of the fastest consumer processors AMD has to offer

The AMD Ryzen 9 3900X also has some impressive specs away from the new architecture, with 12 cores and 24 threads. This exceeds the count of the Intel Core i9-9900K, suggesting AMD’s offering will be superior for multi-core performance when you’re running several intensive applications on the computer. 

The AMD Ryzen 9 3900X also boasts a higher base clock speed of 3.8GHz compared to the Intel Core i9-9900K’s 3.6GHz. One key area where the Ryzen falls short is the boosted clock speed; it can’t quite match the efficiency of the i9-9900K’s 5GHz. 

In layman’s terms, this likely means the i9-9900K still has the edge for gaming, but the Ryzen 9 3900X is the better option for multitasking creatives. However, with all those cores, AMD’s chip has a high thermal design power at 105W, vs the 95W of the Intel chip.

Related: Best Intel processor

AMD Ryzen 9 3900X test setup

In order to benchmark the AMD Ryzen 9 3900X and compare it to other processors, we had to ensure a fair test. To this end, all other components in our computer rig remained consistent. All of the hardware we used can be seen below:

Motherboard: Gigabyte Aorus X570 Master for AMD CPUs/Asus ROG Maximus XI Extreme for Intel CPUs 

GPU: Nvidia GeForce RTX 2080 Ti 

RAM: Corsair Vengeance 2666MHz, 16GB DDR4

Cooler: Corsair Hydro Series H150i PRO RGB 360mm liquid cooler

PSU: Corsair CX750M

SSD: Gigabyte Aorus NVMe Gen4 SSD 2TB 

OS: Windows 10 Pro 64-bit

The benchmark software is also important for testing processors. We ensured that both synthetic and real-time testing processes were used to gain a good idea of the performance power for each chipset. 

For gaming, we chose three games: Shadow of the Tomb Raider, The Division 2 and Dirt Rally. The first two titles are great examples of modern games that demand a lot from PC hardware; I chose Dirt Rally to represent less intensive titles of the type released some years back. 

While those three games test how much the CPU influences the frame rate performance, I also selected Civilization 6 to measure the impact the processor has on loading times for complex AI decisions in grandiose strategy games.

AMD Ryzen 9 3900X performance – One of the best multitasking creatives on the market

AMD’s big plan with the AMD Ryzen 9 3900X was to close the gap between itself and Intel – and in this regard it’s been largely successful. The Ryzen 9 3900X beats the Intel Core i9-9900K for multi-core performance by quite a margin. The extra core count has no doubt had an impact here, proving that out of the two this is the best chip for multi-tasking creative work.

For gaming, it’s another story. In the main, video games rely mostly on powerful single-core performance, and here, clock speeds become more essential than core count – which gives the Intel Core i9-9900K the advantage. 

That’s not to say the Ryzen 9 3900X doesn’t offer superb gaming performance. However, since the Intel Core i9-9900K has benefited from a price cut, it’s the better option for those who will be exclusively gaming, and aren’t really bothered about dabbling in media editing. 

Geekbench 4 and Cinebench

AMD Ryzen 9 3900X

The Geekbench 4 single-core benchmark test measures the single-core performance of a processor. This is often the best synthetic test for gaming performance, since most video games don’t take full advantage of multiple cores. 

The Intel Core i9-9900K boasts a superior single-core score at 5542 according to the Geekbench 4 results, with the AMD Ryzen 9 3900X only mustering 4911. This backs up our in-game benchmark results, with the i9-9900K leading the way with almost every result. 

AMD Ryzen 9 3900X

The advantage swings to AMD for multi-core performance, however. It displays drastically superior results over the i9-9900K in both the Geekbench 4 and Cinebench tests. With the latter test, the Ryzen 9 3900X saw a result of 7184 which is significantly better than the Intel Core i9-9900K reading of 4824. 

It’s here that the Ryzen 9 3900X really shines, proving to be a much better multi-tasker than rival CPUs for juggling multiple media-editing programs. 

PCMark 10

PCMark 10 is a much more holistic test than the other synthetic benchmarks, giving an overall impression of processor performance rather than dissecting it via single-core and multi-core. Intel’s i9-9900K reigned supreme here, but only by a slim margin. 

Fortunately, PCMark breaks down the results into categories, so we can see exactly how the AMD Ryzen 9 3900X performs in different situations. 

The Essentials category is the main reason for Intel’s i9-9900K superior overall score, but this only factors in low-level single-core tasks such as app startup, web browsing and video conferencing; the multi-core advantage of the Ryzen 9 3900X doesn’t come into play. 

For the Productivity and Digital Content Creation categories, the Ryzen 9 3900X comfortably beats the i9-9900K’s results, which is no surprise given its multi-core prowess. Digital Content Creation is a particularly strong area, which covers photo editing, video editing and rendering. If you’ll frequently be taking on such tasks then the Ryzen 9 3900X is definitely a better option for you over Intel’s i9-9900K. 

Shadow of the Tomb Raider

AMD Ryzen 9 3900X

Shadow of the Tomb Raider is a technically demanding video game and a great option for benchmark tests. For Full HD and Quad HD gaming, there’s little that separates the AMD Ryzen 9 3900X from the Intel Core i9-9900K.

It’s a different story on cranking up the resolution to 4K, however. The Intel Core i9-9900K saw significantly better performance, beating the Ryzen 9 3900X by 21fps. This is likely due to Intel’s superior clock speeds, with single-core performance king for gaming. 

Even Intel’s 8th-generation i7-8700K comfortably beat the AMD Ryzen 9 3900X, proving that AMD still has a long way to go to be competitive with Intel for Ultra HD gaming. If you’re content to play at a lower resolution, though, this shouldn’t be a problem. 

The Division 2 

AMD Ryzen 9 3900X

The Division 2 saw some fascinating benchmark results, with the frame rate count being ultra-competitive across every processor at every resolution. 

There are several reasons that the AMD Ryzen 9 3900X sees a similar performance to the Intel Core i9-9900K, even at 4K. This could be because The Division 2 utilises a multi-core performance more so than most other gaming titles, which gives the Ryzen an advantage. Another explanation could be that this Ubisoft game is so demanding on the GPU that the change in processor doesn’t really make much of a difference in performance.

Whatever the reason, The Division 2 is a compelling example to prove the AMD Ryzen 9 3900X is a worthy processor for high-end gaming and Intel doesn’t always boast a significant lead. 

Dirt Rally

AMD Ryzen 9 3900X

Dirt Rally was released back in 2015, and so for modern hardware it won’t prove a demanding video game. But this also means the CPU can have a noticeable impact, making this a great benchmark test. 

The Intel Core i9-9900K had a clear lead over the AMD Ryzen 9 3900X, particularly in the 4K test, with the former ahead by 22fps. This supports the argument that clocks speeds are far more influential than core count for games released a number of years ago. If you’re planning on playing through a backlog of old games, the Intel CPU here certainly represents better value. 

That said, these AMD Ryzen 9 3900X scores are still very impressive. If you want a versatile chip that’s capable of a high performance for both media editing and gaming, this Ryzen chip will no doubt do an excellent job. 

Civilization 6 

AMD Ryzen 9 3900X

The Civilization 6 benchmark test measures a different kind of gaming CPU performance. It focuses on the time it takes for the AI to make its calculations and take its own turn in turn-based strategy games, rather than the frame rate. 

Since we’re essentially talking about loading times here, the lower the result the better. This means the Intel Core i9-9900K once again is victorious. This doesn’t necessarily mean that Intel’s chip will also be the superior option for strategy games, however. Some modern titles make more use of multi-core performance, which would give AMD’s chip a boost. 

Related: Intel Core i9-9900K review

AMD Ryzen 9 3900X – Power consumption and heat 

The difference in power consumption between the AMD Ryzen 9 3900X and Intel Core i9-9900K is interesting, with the former leaching significantly more power when idle at 111.8 watts compared to the i9-9900K’s 69.2 watts. However, Intel’s chip proves more power-hungry when called into action for intensive tasks, consuming 261.1 watts over AMD’s 234.2 watts.

AMD Ryzen 9 3900X AMD Ryzen 7 3700X Intel Core i9-9900K Intel Core i7-8700K
Idle (W) 111.8 89.5 69.2 78
Cinebench (W) 234.2 166.1 261.1 153.5

The explanation for this is once again likely due to the difference in core count, with the AMD Ryzen 9 3900X requiring more wattage to power is 12 cores for the majority of the time. But when the processor is needed for a difficult task, it doesn’t need to call in as much extra power as the Intel Core i9-9900K, which is more reliant on driving up clock speeds. 

In terms of what’s more eco-friendly then, it really depends on your use of the desktop. If you’re regularly doing video editing and animation work, then the AMD Ryzen 9 3900X is more power-efficient. If you’re more likely to be playing games and tackling low-performance tasks such as web browsing and word processing, the Intel Core i9-9900K looks the better option. 

AMD Ryzen 9 3900 X

I saw inconsistent results when it came to thermal performance. When using the stock fan, I saw the AMD Ryzen 9 3900X occasionally raise up to 95°C when running or playing intensive games/software. Fortunately, the Wraith Prism RGB stock cooler has a physical switch which speeds up the fan and does a better job at cooling down the CPU. The downside of this is that the fan can get really loud – to the point it will start annoying you unless you’re rearing a pair of headphones.

While a third-party fan isn’t necessary at all, I did find the Corsair Hydro Series H150i PRO RGB 360mm liquid cooler to slightly improve performance results while also remaining significantly quieter. This is by no means a cheap solution, but it’s still worth the buy to maximise the performance and lifespan of the CPU. 

AMD Ryzen 3900 X Overclocking – Can you overclock it?

I didn’t have high hopes for the AMD Ryzen 3900 X overclocking potential. Because of time constraints, I was also limited to how much tweaking I could do and therefore kept to all-core overclocking rather than boosting the performance of each core individually. 

I used AMD Ryzen Master, syncing up all the cores and manually raising the clock speed incrementally to prevent a sudden overheat. 

The highest clock speed I could achieve with all 12 cores simultaneously without the computer crashing was 4.4GHz, which is actually lower than AMD’s claimed 4.6GHz boost clock speed. Of course, AMD’s figure likely represents the max clock speed achieved by a single core which would explain why I couldn’t push all 12 cores quite so high. 

Such an overclock gave a massive boost to the multi-core performance, with Geekbench 4 benchmark result rising from 35,849 to 37,437, further strengthening AMD’s dominance over Intel in this area. 

Performance wasn’t stable though with temperatures hitting 75°C. I found the system to crash with the processor overclocked to these speeds when running more intensive benchmark tests such as PCMark 10 and Cinebench. 

With this in mind, you’re probably better off sticking to default settings, as the gains you’re getting aren’t really worth sacrificing the length of the chip’s lifespan.

Should I buy the AMD Ryzen 9 3900X?

When the AMD Ryzen 9 3900X first launched, it undercut the Intel Core i9-9900K and offered supremely better value. This has changed now, though, with Intel’s chip the cheaper option after receiving a particularly hefty price cut. 

With the Intel Core i9-9900K being £50 cheaper and offering superior gaming performance, especially at 4K resolutions, there’s no doubting that it’s the better-value processor compared to the AMD Ryzen 9 3900X if you’ll be using your desktop for gaming and little else. 

AMD Ryzen 9 3900 X

The AMD Ryzen 9 3900 X is built using a 7nm manufacturing process

The AMD Ryzen 9 3900X still has plenty of appeal, with it’s multi-core performance trouncing Intel’s offering in this area. This results in a processor that excels in high-performance media tasks such as video editing, animation and anything else that takes advantage of the chips 12 cores. 

As such, the AMD Ryzen 9 3900X is a versatile processor and, arguably, the best premium option in the consumer market – as long as you’ll be taking full advantage of those 12 cores. 


For demanding creative tasks, the AMD Ryzen 9 3900X is one of the best processors available thanks to a super-high multi-core performance. It’s also a versatile chip, with gaming performance proving to be solid – although the Intel Core i9-9900K still holds the advantage here if you’re looking for a CPU for your dedicated gaming rig.

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