Ryzen 7 5800X vs Ryzen 9 3900X: What are the Key Differences?

AMD’s Ryzen 5000 series CPUs have stormed the market and made their mark as affordable processors that pack a whole lot of punch for the price. However, consumers shouldn’t look just at these new and shiny CPUs for their builds. The Ryzen 3000 series dominated the market in 2019 with powerful multi-thread CPUs that can still stand up, in some ways, to the performance of the new Zen 3 based Ryzen 5000 series chips. 

The 3000 series aren’t processors that should be skipped over solely due to them being from a previous generation. AMD’s focus was more centered on packing a ton of threads and cores into their CPUs, even more so than the current generation’s offerings. With both chips being based on AMD’s dense 7nm node infrastructure, there is a lot of value to be had in the Ryzen 3000 series in 2021. Specifically, the Ryzen 3900X has a few competitive legs up on the recently released Ryzen 5800X.


CPURyzen 9 3900XRyzen 7 5800X
DesignAMD Ryzen 9 3900XRyzen 7 5800X
Base/Boost GHz3.8/4.63.8/4.7
L3 Cache64MB32MB
Included CoolerWraith PrismNo

Cores & Threads – Tie

A cursory glance may lead many to believe that the Ryzen 9 3900X dominates the competition in terms of cores and threads. After all, this previous generation CPU packs 12 cores and 24 threads compared to the Ryzen 7 5800X’s 8 cores and 16 threads. The raw number of cores and threads isn’t the sole metric here. AMD has improved upon the infrastructure of the CPU’s core design to deliver lightning-fast performance with fewer cores and threads with the 5000 series CPUs. That being said, the Ryzen 9 3900X’s vast core count does have its advantages. 

The Ryzen 9 3900X pulls ahead and offers faster multi-thread performance in tasks such as heavy rendering, video editing, and other workstation workloads. In those cases, the higher core and thread count makes for better performance. On the other side of things, the Ryzen 7 5800X’s improved design leads to much faster single-thread performance. Gamers looking to just buy a CPU that can deliver faster frame rates will want to avoid the Ryzen 9 3900X in favor of the much faster Ryzen 7 5800X. But that isn’t the end-all-be-all of this comparison yet. The Ryzen 9 3900X has a few more tricks up its sleeve for the more work-focused consumers out there.

Clock Speeds & L3 Cache – Ryzen 9 3900X

AMD Ryzen 9 3900X

Out of the box, performance is nearly identical between the two CPUs. The Ryzen 9 3900X sports base speeds of 3.8GHz with overclocking bringing that figure to 4.7Ghz with a bit of tuning. The Ryzen 7 5800X starts at the same 3.8GHz while climbing up to a slightly higher figure at 4.7GHz. The difference in base speeds is almost negligible, though both CPUs are very user-friendly when it comes to overclocking. AMD allows for auto-overclocking in the BIOS settings right from the start, so users won’t be left trying to navigate confusing menus or complex programs just to get that boosted performance. 

Turning to other metrics for raw performance is a must with such similar neck-to-neck performance in terms of clock speeds. The L3 cache, or what AMD deemed the “GameCache” with the 3000 series release, allows for better performance in games or programs that frequently draw from short-term stored memory. The larger the cache, the quicker these tasks can be performed since the CPU doesn’t have to communicate with other forms of onboard memory like RAM. 

The Ryzen 9 3900X sports a massive L3 cache with 64MB while the Ryzen 7 5800X has just 32MB. Both L3 caches far outpace the comparable Intel offerings from both generations. But the Ryzen 9 3900X’s is far more robust, doubling the memory of the 5000 series CPU. With both CPUs able to make the most of the DDR4-3200MHz memory, the Ryzen 9 3900X pulls out of this metric ahead. 

TDP & Included Cooling – Ryzen 9 3900X

AMD Ryzen 9 3900X

The top-of-the-line previous generation Ryzen 9 3900X and Ryzen 7 5800X share the same base TDP of 105W. Putting the chips through their bases may bring that number up to a peak of around 125W, but neither CPU will put nearly as much power as the offerings from Team Blue. What may make the Ryzen 9 3900X a slightly better value is that it is an enthusiast CPU that actually comes packaged with a cooler that can easily handle the heat it generates. 

The Wraith Prism RGB is a four heat pipe cooler with multiple fan modes, RGB, and software to control all of those features. It’s a solid stock cooler that will be more than enough for consumers looking to get the most bang for their back. Meanwhile, the Ryzen 7 5800X does not come with any sort of included cooling solution.

MSRP – Ryzen 7 5800X

Ryzen 7 5800X

The price is where things get a little tricky. The Ryzen 9 3900X retailed at $499 in 2019, and most online retailers like Amazon are hanging on to that figure. However, those looking for deals can find many second-hand options for as low as just a few hundred dollars. Now, buying second-hand hardware, particularly electronics, comes with a risk and any warranty will be long voided. But it is worth noting that there is much more available in that market than there is for the newer Ryzen 7 5800X. The newer CPU retails at $449, making it slightly less expensive than its previous generation counterpart. That’s only if you are lucky enough to pick the Ryzen 7 5800X while it is both in stock and available at MSRP.

Verdict – Ryzen 7 5800X

Ryzen 7 5800X

It’s difficult to say with certainty that one of these CPUs is the hands-down best option for every consumer or enthusiast. The Ryzen 9 3900X offers a very different feature set that is more tailored towards multi-thread tasks, workstations, and productivity. The Ryzen 7 5800X slides ahead with stellar gaming and single-thread performance. Despite being outclassed in L3 cache and base cores/threads, the Ryzen 7 5800X will be the best middle-ground for enthusiasts going back and forth between the two CPUs. It’s hard to go wrong with either option, but the Ryzen 7 5800X offers a better blend of single and multi-thread performance at a slightly more affordable price point.

Best Component Pairings for the Ryzen 9 5950X

Your build doesn’t end with the CPU. Your component journey has just begun. Those looking to get their hands on the Ryzen 7 5800X will need similarly powerful and reliable components to make the most of it. Take a look at a few of our guides for the best motherboards, CPU coolers, and graphics cards for this fast 5000 series CPU. You can even take a look at our Ryzen 7 5800X gaming build for a no-compromise machine that can deliver top-of-the-line gaming performance.

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