AMD Ryzen 9 3950X Review

Written by Antony Leather

November 14, 2019 | 14:00

Tags: #3rd-gen-ryzen #7nm #hedt #ryzen #ryzen-9-3950x #socket-am4 #x470 #x570 #zen-2

Companies: #amd

Manufacturer: AMD

UK price (as reviewed): Approx £700 (inc. VAT)

US price (as reviewed): MSRP $749 (exc. tax) 

The Zen 2 architecture has been the talk of 2019, and it's certainly had a huge impact. However, it was arguably not the 3rd Gen Ryzen range of CPUs as a whole that had the most impact on the desktop CPU market this year. Massive price cuts, HEDT-matching specifications from a mainstream CPU, and a complete re-write of the HEDT market as a result have all been thanks to one processor. The Ryzen 9 3950X is right up there in terms of mega shake-ups. In fact, there are plenty of reasons to argue it's the most disruptive CPU we've ever reviewed. Feel free to hit the comments section on that one.

Model Cores/Threads Base Freq Boost Freq Total Cache TDP (Watts) Included cooler SEP (USD) Availability
Ryzen 9 3950X 16/32 3.5GHz 4.7GHz 72MB 105W None $749 November 25, 2019
Ryzen 9 3900X 12/24 3.8GHz 4.6GHz 70MB 105W Wraith Prism RGB $499 July 7, 2019
Ryzen 7 3800X 8/16 3.9GHz 4.5GHz 36MB 105W Wraith Prism RGB $399 July 7, 2019
Ryzen 7 3700X 8/16 3.6GHz 4.4GHz 36MB 65W Wraith Prism RGB $329 July 7, 2019
Ryzen 5 3600X 6/12 3.8GHz 4.4GHz 35MB 95W Wraith Spire $249 July 7, 2019
Ryzen 5 3600 6/12 3.6GHz 4.2GHz 35MB 65W Wraith Stealth $199 July 7, 2019

The key point here is that there's every reason to suspect that the extra cores will translate into scalable performance. This hasn't happened elsewhere in AMD's range; the Threadripper WX-Series, for example, suffered from latency problems due to some dies lacking direct access to the memory and PCIe bus, so in many instances, those extra cores really didn't hit home or equate to anywhere near the multi-threaded performance they should have. Similarly, even once various gremlins such as Nvidia driver bugs were fixed, it was still a poor performer in many lightly threaded tasks. Seeing as the Ryzen 9 3950X is "simply" a 3900X with no disabled cores and an otherwise identical topology under that familiar heat spreader, then assuming the software also scales with cores and threads and boost behaviour isn't wildly different, there should be a hefty bump in performance. 

What makes the Ryzen 9 3950X extra special is that it also tops the 3rd Gen Ryzen chart with the highest peak boost frequency of any Zen-based desktop CPU at 4.7GHz, meaning that it not only offers the best multi-threaded performance but also the best potential single-threaded performance too. Where things do tail off, though, are in the observed all-core boost frequencies. There's always variation between samples, but our Ryzen 9 3900X usually sat at around 4.05GHz under full load whereas this 16-core model dipped down to 3.9GHz once all cores were loaded for extended periods, occasionally spiking to a little over 4GHz. That means that there's potentially a lot of multi-threaded performance to gain from overclocking, especially if AMD has indeed delayed the CPU to bin enough CPUs to hit these higher frequencies in the first place - we're hopefully dealing with some of the highest quality silicon AMD has in this market.

In any event, the frequencies and core counts involved here from this 32-thread monster mean that it's probably not even really competing with the likes of the 8c/16t Core i9-9900KS, at least not outside of games, and the two are indeed priced rather differently, with the Ryzen 3950X expected to be around $250/£200 dearer than Intel's LGA 1151 flagship and thus priced against the new 10th Gen Cascade Lake-X parts due to launch in a mere nine days alongside 3rd Gen Threadripper - to say that November is exciting for high-end desktop CPU performance would be a drastic understatement. Note that our UK pricing on this part is at the time of writing a best-guess estimate based on the US MSRP converted to GBP with 20 percent added for tax.

Back to the CPU in question, and the rest of the specifications are similar to the Ryzen 9 3900X, with 72MB of so-called GameCache split between 8MB L2 cache coming from 512KB per core, equating to 2MB per CCX and 4MB per CCD and two CCDs in total sitting next to the I/O Die. While the two CPUs share the same 16MB L3 cache per CCX, giving a total of 64MB, the fact that four cores are disabled on the 12-core SKU means that it loses 2MB of L2 cache, so "only" has 70MB. 

AMD doesn't supply a cooler with the Ryzen 9 3950X, and as a result, the box is half the size of the one used with the Ryzen 9 3900X, housing the latter's Wraith Prism RGB cooler. It seemed a little anticlimactic given what we hope the CPU is capable of. AMD is well known for fanfare, but it was surprisingly lacking here. With a 105W TDP, the stock speed power draw and subsequent heat output are hopefully a fraction of its HEDT counterparts, which adds further to its appeal, although AMD is promoting various twin-fan 280mm AIO liquid-coolers as suggested partners, especially those wanting to head into the EFI for some frequency tuning.

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