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

Can the 3900X beat the 9900K to become the best gaming CPU in the world?

AMD Ryzen 9 3900x
Dan Baker/Digital Trends

2019 has been a great year for AMD, with new CPU and graphics card launches that are capturing massive attention from the industry and hardware fans as a whole. 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 and 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

Only eclipsed by its incoming 16-core brethren, the Ryzen 9 3900X is the most powerful mainstream CPU AMD has ever released, and it has some fantastical specifications. The Core i9-9900K is no slouch though, 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) 4.6GHz (single core) 4.1GHz+ (all cores)
Graphics Intel UHD Graphics 630 No
TDP 95w 105w

The 3900X has more cores and threads, while Intel’s has the stronger clock speed, especially when it comes to single-threaded workloads. Most games utilize a handful of cores in 2019, though, 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 that is 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 is 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 has beaten the Intel competition in gaming for more than ten years. This is momentous news.

That said, Intel’s 9900K is the cheaper of the two chips at this time. The 9900K can be had for $490, but its onboard-graphics-free alternative, the 9900KF is priced as little as $480. In comparison, supply issues have pushed the 3900X up to as high as $560. While it might be th

That might make Intel’s option more value for money, at least in gaming. It is important to consider the ongoing problems Intel has faced with performance of its CPUs being inhibited by Spectre mitigation, though. 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 multi-threaded 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 AMD showed off 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 got our hands on the 3900X we pitted it against its true rival though, 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 percent 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 with mobile, as there’s no battery life to be concerned with. That said, 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 though 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.

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 and we’re happy to report that post launch, after having tested it, we’re even happier. The 3900X offers comparable performance to the 9900K in gaming and limited thread tasks, even eclipsing it in some cases, and it obliterates 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 the red team 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 and it’s reduced prices in turn to help it stay competitive. That and supply concerns with the 3900X do make it the more expensive chip by up to $80. That is worth spending if you’re going to take advantage of its additional cores, but if you’re purely interested in gaming, the lower cost of the 9900K is definitely worth considering instead.

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