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AMD Ryzen 9 3900X vs. Intel Core i9-9900K: Spec comparison

2019 was a great year for AMD, with new CPU and graphics card launches that captured massive attention from the industry and hardware fans alike. But that’s not to say it doesn’t have stiff competition in both camps. Its new Ryzen 3000 CPUs go head to head with Intel’s best on price, but how do they compare on performance?

With new hardware in hand, there are great comparisons for us to make throughout the new range of Ryzen chips. At the top end, for around $500, we have the Core i9-9900K versus the Ryzen 9 3900X. Which will be the best chip of them all?

By the numbers

AMD Ryzen 9 3900x
Dan Baker/Digital Trends

Only eclipsed by its 16-core successor, the Ryzen 9 3900X is an extremely powerful mainstream CPU packing fantastic specifications. The Core i9-9900K is no slouch, however, and by the numbers, they’re pretty comparable.

Intel Core i9 9900K AMD Ryzen 9 3900X
Process node 14nm 7nm
Cores 8 12
Threads 16 24
L2/L3 cache 2MB/16MB 6MB/64MB
Base clock speed 3.6GHz 3.8GHz
Boost clock speed 4.7GHz (all cores)
5GHz (one core)
4.1GHz+ (all cores)
4.6GHz (one core)
Graphics Intel UHD Graphics 630 No
TDP 95w 105w

The 3900X has more cores and threads, while Intel’s chip has the stronger clock speed, especially when it comes to single-threaded workloads. Most games now use a handful of cores, so unless you’re overclocking, you won’t typically see 5GHz frequencies when gaming on a 9900K.

The 3900X can boost to 4.6GHz on a single core, but will be closer to 4.1GHz if using all cores and threads at the same time. AMD’s automated overclocking can take it up to 4.3GHz in some cases, though it’s very much dependent on your motherboard, BIOS revision, and cooling.

The 3900X has seen a major increase in instructions per clock over its second-generation predecessors, so it’s more powerful than the 9900K clock for clock. Its huge L2 and L3 cache effectively eliminate the memory latency concerns from the 2nd-generation chips too.


Intel Core i9- 9900K
Intel Core i9- 9900K

Intel has held a performance edge in gaming for more than a decade, and even with AMD’s fantastic first- and second-generation Ryzen CPUs, that held true. But no longer.

In our gaming tests with Fortnite, Civilization VI, and Assassin’s Creed Odyssey, the 3900X beat out the 9900K — a CPU previously hailed as the best gaming chip ever made — on almost all settings, showing a slight lead. That might not be the crushing numbers that AMD fans hoped for, but this is the first time that a high-end AMD CPU beat the Intel competition in gaming for more than 10 years. This is momentous news.

That said, AMD’s 3900X is the cheaper of the two chips at this time at $434, while the 9900K sells for around $525. Intel’s onboard-graphics-free alternative, the 9900KF, is priced as low as $480, which is still higher than AMD’s chip — at least for now. That makes AMD’s option more value for money, at least in gaming.

It is important to consider the ongoing problems Intel faces with CPU performance hindered by Spectre mitigation. Those may continue as new bugs are found in the future, where AMD’s chips are typically more robust against these kinds of exploits.


Heavily multithreaded productivity tasks like video transcoding and editing have been more AMD’s wheelhouse for the past couple of years, with its Ryzen and Threadripper chips competing directly and even pulling ahead of Intel’s more expensive options. With the 3000 series, and specifically the 12-core, 24-thread 3900X, AMD has beaten not only Intel’s mainstream chips (the 9900K included) but will even put some of its older Threadripper cousins out to pasture.

At E3 2019, AMD provided statistics of its 3900X pitted against one that’s more than twice the price: The 12-core, 24-thread, $1,200 Intel Core i9-9920X. And it still cleaned up.

When we received the 3900X for testing, we pitted it against its true rival: The 9900K. Unsurprisingly, the new AMD CPU proved dominant once again.

In Geekbench and Cinebench, the 3900X decimated the 9900K in multithreaded performance, though its reduced clock speed meant it fell just shy of the Intel competition in single-threaded tasks. In the real world Handbrake 4K transcoding test, the 3900X proved almost 25% faster than the 9900K — a sizeable advantage delivered by the extra cores/threads of the AMD chip.


Efficiency isn’t as important on desktop chips as it is with laptops, as there’s no battery life to consider. But heat is an important factor, and the more power a CPU requires, the more heat it outputs. That’s where the somewhat marketing-driven TDP figure comes from.

By the numbers, Intel’s 9900K is the more efficient chip, with a rated TDP of 95 watts, while the 3900X has a TDP of 105 watts. But that’s not the full story. Intel’s TDP ratings tend to relate to its base clock, rather than its sustained boost. AMD’s are much closer to the power it pulls when at its highest clock speeds.

Research into power demands from Intel’s 9900K around its launch showed it drawing far more power than its TDP rating. Tom’s Hardware reported that while it remained under its TDP during gaming, when doing heavily multithreaded workloads over prolonged periods, it could require more than 200 watts. That number could increase to 250 watts if overlocked.

We didn’t test the 3900X’s power draw, but other reviewers have, and Anandtech found it never pulled more than 142 watts when fully loaded. That makes it a more efficient chip than the 9900K too. And that’s AMD’s big selling point with its Zen architecture: More performance per watt.

The 3900X is the new CPU king

AMD Ryzen 9 3900x
Dan Baker/Digital Trends

We were excited for the 3900X before it launched based on prerelease numbers and speculation. Now we can report that after tests, we’re even happier.

The 3900X offers comparable performance to the 9900K in gaming and limited thread tasks, eclipsing it in some cases and obliterating it in multithreaded workloads. It does so at a lower TDP too, meaning it draws less power and requires less cooling for its highest performance.

The 3900X is the best mainstream CPU AMD has ever made and hails a return to the top-tier performance that we haven’t seen AMD achieve since the days of the Athlon 64.

Intel now finds itself in the reverse of the position it has enjoyed for more than a decade. In retaliation, it’s reduced prices to help stay competitive.

Unfortunately, for now, that price hack doesn’t save its eight-core 9900K in this scenario. For $91 less, the 3900X offers more cores, more threads, and better performance. The only drawback here is that AMD’s chip doesn’t include integrated graphics, which may be a huge deciding factor when building a PC.

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