3900X vs 9900K

AMD v Intel - the historic battle continues

3900x vs 9900k
Last Updated:

It’s been over two years since Intel released their magnificent i9 9900K CPU, and it’s been well over a year since AMD released their 3000 series, but the war between these two beloved processors is far from over. Millions of gamers are still undecided on which they’ll use for their next build.

With both companies having just released more powerful iterations of their flagship designs, now, as prices are falling, is the best time to consider which of these processors is right for you and your system.

Adding fuel to the fire, making this a battle for the ages, we’re going to be pitting these two giants against one another in head-to-head combat. They’ll be duking it out over raw specs, clashing swords over components, going blow for blow in performance, and showing down to prove their value. Let’s get ready to ruuuuumble!

Key Specs

Before we run these two gladiators against each other in bloody electrical combat, let’s take a look at the advertised SKUs. 


Fighting in the blue shorts with a total of 8 cores, we have the 9900K. Fighting in the red shorts, with an impressive 12 cores, we have the 3900X. DING DING DING!

The Ryzen comes out on top in the first round as far as dry SKUs are concerned. Generally speaking, the more cores a processor contains, the more complex commands it can execute, leading to faster, smoother overall performance, especially during a parallelizing workflow.

Core count isn’t everything, but a lot of modern software is designed to leaf out tasks to as many cores as are present, meaning that if there aren’t enough, the functionality of the software will be crippled.


Both these processing pugilists have been kitted out with multithreading capabilities. But the 3900X works the 9900K against the ropes in this second round, as well as the 12 cores double up to 24 threads. Obviously, the 9900K maxes out at 16 threads.

At this juncture, in terms of raw fundamentals, there’s a pretty clear winner in the Ryzen 3900X, but then why are these two CPUs so compared and argued over? Well, let’s begin the speed round and get to the bottom of their contentious history.

Clock Speed

Boasting a solid base clock speed of 3.8GHz, the 3900X shows us some pretty fiery footwork, and the Intel CPU lags marginally behind, clocking in with a base frequency of 3.6GHz. Another win for AMD, it seems, but here’s where things get interesting.

The 3900X has a maximum boost frequency of 4.6GHz. Push the 9900K to its limits, and you hit a very impressive 5GHz maximum boost frequency.

Hypothetically, if both CPUs had sufficient cooling to facilitate their max clock speed for long periods of time, you’d notice a slightly more responsive performance from the 9900K.

So, we’d claim that Intel takes this round, although it’s important to note, the performance provided by the clock speed will be fractionally offset by the core count. You could also say its slower max clock speed offsets the Ryzen’s core count.

Both these CPUs can be overclocked, but again, the 9900K comes out on top, as the 3900X doesn’t have as much overclocking headroom.


A lot of modern gaming requires quite a bit of fast-link memory to run at an acceptable rate. Caches are memory banks that sit in front of your RAM and act as these quick-access storage zones. A good cache capacity is recommended if you’re playing with a resolution below 4K.

With an L1 capacity of 768KB, and L2 with 6MB, and an L3 with 64MB of memory, not to mention the 3200MHz DDR4 memory type, the 3900X really shows its metal here.

The 9900K has a single L3 Smart Cache with a 15MB capacity supported by a 2666MHz memory speed.

This is a big win for the Ryzen, but let’s put the components of these two dauntless CPUs under the microscope next and see which comes out on top of the hardware game.


You should never base your purchase on pure specs alone. You’re not just buying a CPU, you’re buying a multitude of different components that make up a CPU, and although these CPUs are often compared, they’re made of very different things.

So, let’s take a look at some of the individual pieces that come together to make the magic happen.

Onboard Graphics Capabilities

First, let’s confront the glaringly obvious difference between these two CPUs. The i9 9900K comes with a preloaded silicon UHD integrated graphics card. The Ryzen 9 3900X comes with absolutely no on-chip graphics capabilities.

On the surface, this seems like a pretty big ‘W’ for Intel, but considering gamers are likely to have already primed their computers with a high-performance graphics card, the absence of onboard facilities in the 3900X probably won’t matter too much.

Onboard Cooling

Another huge defining factor between these CPUs is onboard cooling. The Ryzen 9 comes with the awesome LED-laden Wraith Prism thermal solution, whereas the Intel i9 9900K has nothing in the way of integrated cooling.

So, turning the tables here, this seems like a big ‘W’ for AMD. We wish it was as simple as that. Yes, the Wraith Prism is a good standard cooling system, but is it going to support the Ryzen 9 running at its limits for extended periods of gameplay? No.

If you really want to push these CPUs, you’ll need to buy separate cooling systems for both.

PCI Express

The AMD 9 3900X more than redeems itself in this department. It features a 4.0 x16 PCI-E while the Intel i9 9900K sports its predecessor, the 3.0 x8 PCI-E. PCI Express defines how you can augment your system with external hardware such as video cards or extra storage SSD cards. 4.0 PCI-E is cutting edge technology, and this series of AMD CPUs are some of the very first tech products to feature it.

Basically, 4.0 x16 refers to a greater bandwidth over the same series of lanes, which leads to faster data transmission between components.

If you’re building your computer from scratch yourself, the 3900X might be worthwhile, purely because of this technology. It will allow more significant customization as you streamline your final build. You can consider it an investment in your techy future as it will be compatible with new hardware for years to come.

Of course, cutting edge technology comes hand in hand with a few compatibility problems while other aspects of the tech world play catch up. To support PCI Express 4.0, you’ll need a motherboard that allows it to work at full capacity.

It’s not game over if you can’t afford to or don’t want to replace your current motherboard. The PCI Express 4.0 will still work, but it won’t run as the 4.0 is designed to.

When you use a more advanced PCI Express in an older port, the motherboard defines the parameters of performance; thus, it will function like a 3.0 despite being a 4.0 bit of gear.

A Note On Connectivity

Intel comes out fighting with a second wind in terms of connectivity. Their proprietary Thunderbolt 3 interface is compatible with plenty of their motherboards, and it can support additional hardware at super-fast speeds up to 40GBps. This means you’ll be able to sync up an 11th gen Intel CPU that supports 4.0.

AMD and, in fact, a lot of tech companies don’t want to pay out to Intel for the rights to use the Thunderbolt 3 (or even 4 now) technology in their systems. This is a big downside to the AMD setup, especially if you’re interested in hooking up hardware that requires very low latency, such as music interfaces.

But enough with these cold hard specs and components. How do they all come together in a way that affects your gaming experience? Let’s get into it!



Thanks to an impressive base clock speed the 9900K is probably better if you still play a lot of older games, especially if you have a great video card. The faster-boosted rate also means it’s better for what is known as bursty workflows.

Bursty describes a process in which information is received in regular or irregular squarewave-shaped influxes.

It’s not just old games that the i9 9900K excels at. When tested against one another running a myriad of different games, the 9900K beats the 3900X in facilitating frames per second almost every single time running at both stock clock speeds and overclocked speeds.

The gap was pretty insubstantial in some games, not really perceivable just sitting down and playing. World War Z showed the Intel CPU perform 2% faster, stock and overclocked.

Racing games like Forza Horizon 4 doubled the i9s lead to 4%, still nothing to swoon over, especially as the 3900X managed to halve the difference while overclocked.

Unfortunately for AMD, with other games, the 3900X eats the i9 9900Ks dust. Games like Shadow of the Tomb Raider, Apex Legends, and Fortnight all saw the 9900K zoom off ahead, while the 3900X dropped frames left and right.

The widest gulf opens up between these two CPUs when playing large scale multiplayer strategy games. Starcraft is one of our personal favorites so we checked out frame rate performance for a full four-team multiplayer game and discovered the i9 9900K runs 19% faster than the 3900X, both with factory settings. Overclocking both reduced the gap to 12%.

It wasn’t all doom and gloom for AMD, as the 3900X did slightly outperform the 9900K in a few games such as Monster Hunter and Counter-Strike Global Offence.

It’s also important to note that although the 3900X was losing most of these face-offs, the difference in frame rate was so minuscule, you wouldn’t notice in a million years. 

So, the Ryzen takes a loss here, but only if you’re running games in 1080p. At 4K the performances were fairly level. What did impress us is the capacity of the 3900X’s supposedly small overclocking capabilities, and even if it is a marginally slower CPU unless you’re a hardcore professional gamer, you really don’t need the extra frames per second. 


If you subject these two CPUs to a Cinebench R15 test that assesses core workflow, you discover something quite interesting. When it comes to multi-core performance the 3900X comes out on top by a significant amount, which makes perfect sense. It has far more cores.

When you challenge individual cores, the 9900K actually comes out on top here. As impressive as this is, it’s not going to have much of a bearing on gameplay. The 3900X has far more resources for running demanding software.

The 3900X is going to be much more capable of seamless rendering due to those extra cores and threads, so if you use your gaming computer for other demanding software like complex video editors or 3D animation programs, the Ryzen is the one for you, hands down. It’s not even a question.

If you like to stream your gaming on Twitch, or you like to watch streams while you play, the 12 core, multi-thread 3900X is by far the more competent CPU. It will handle all the encoding tasks involved with multitasking while keeping your framerates at a playable level.

Even though the 9900K is a much faster CPU on most occasions, the FPS would drop dramatically when made to run game and video functions simultaneously.

So, now that we’ve done a deep dive on playability, let’s take a look at how much you can expect to pay out for one of these bad boys.

Breaking Down the Cost

When these CPUs originally hit the market, they were both priced around the $500 mark. As you’d expect, in the light of new releases, both CPUs have lost some stock value, but it’s interesting to note that the 3900X has retained a higher market price than the 9900K.

There’s less than $100 between them, but considering Intel’s original i9 price point, that’s a pretty severe reduction. So it seems Intel is the one to go for on a budget, but you should ask yourself why it hasn’t held as much value as the AMD CPU.

It’s likely due to the future proof architecture of the 3900X. Simply put, the AMD CPU has retained more relevance thanks to the 12 cores and PCI Express 4.0.

Let’s not forget, a CPU is rarely a singular purchase. You’ll need the appropriate motherboards to unlock their true potential, so you should factor their cost into your decision as well. There are a few compatible boards for each of these CPUs now, found between $150 and $400.

A liquid cooling system might also be on the cards if you plan on really pushing these CPUs. That will set you back $300 or more.


It’s a complex debate, but if we’re being really honest with ourselves about value, relevance, and overall performance, even though it’s more expensive, the Ryzen 9 is the best bang for buck CPU. But that doesn’t mean it’s right for you.

If you’re looking for pure single-core speed, the i9 9900K is definitely the way to go, and the Thunderbolt connectivity of compatible motherboards makes for some awesome zero-latency peripheral connections.

That said, with the multitasking capability of 12 cores over 8, the Ryzen 9 3900X is a far better choice if your games support multithreading.