AMD Ryzen 9 3900XT

A last gasp from AMD’s Zen 2 architecture leaves Alan Dexter both underwhelmed and hotter than normal under the collar.

- Alan Dexte

The AMD Ryzen 9 3900X was released in July 2019, and it was great (see Reviews, LXF259). Loads of cores and decent gaming performance made it a favorite. On paper, this brand new Ryzen 9 3900XT takes that impressive chip and squeezes just a little more power out of it. The base clocks are unchanged at 3.8GHz, but the boost goes from 4.6GHz to 4.7GHz. Yup, a whole 100MHz.

You may be wondering how AMD has managed to produce an extra 100MHz out of this chip, even if it’s only at boost. Apparently, it’s down to a better understanding of the 7nm production process. There are no other changes, though. The core and thread counts are the same, the cache levels are unchanged, and there are no tweaks to the underlying architecture.

What is different, compared to the existing 3900X, is that you don’t get the Wraith Prism cooler with the 3900XT. So essentially you gain 100MHz to the boost clock and lose a cooler for the trouble.

Tap that raw power

The Ryzen 9 3900XT, like the 3900X before it, is a beast of a mainstream processor. Twelve cores and 24 threads give you lots of raw power if you’re a content creator that needs to produce videos and/or dabble in some 3D rendering. The only problem here is the 3900X, which really isn’t that far behind. You’re looking at a four per cent difference in video encoding, and three per cent in the multi-core result from Cinebench R20. So, not a lot.

For testing, we used a Corsair iCue H115i RGB Pro XT all-in-one cooler to keep the chip chilled, and the 3900XT did manage to hit its rated boost speed, topping out at 4.725GHz, with the overall CPU temperature topping out at 79°C. It tends to hit its maximum frequency only very briefly though, and for more thread-conscious loads the chip operates at around 4.2GHz.