How Many Cores and Threads Do We Need?
OK, AMD, YOU WIN: All the cores and threads belong to you. What started with Ryzen several years ago has culminated in a monstrous 64-core/128thread chip, double what was available in the previous second-gen Threadripper parts. They easily eclipse anything Intel has to offer. There’s only one small problem: Most of us really don’t need this many cores or threads.
Threadripper 3990X is a chip built with specific workloads in mind, and if you’re not using one of those workloads, performance can actually be worse than its “little brother” 3970X, which has half as many cores and threads. I’m not talking about the slightly lower clock speeds either.
The 3990X takes AMD’s currently largest Epyc design, disables half of the eight memory channels, then wraps up it in a “consumer” package. Except, with a price of $3,990, plus the need for more RAM and a very high-end motherboard, this takes the HEDT (high-end desktop) market to new extremes. It’s not for home users, or even enthusiasts—it’s built for professionals. More specifically, it’s built for professionals who do a lot of 3D rendering.
You might think just about any multithreaded workload would run better on the 3990X than the 3970X—twice as many cores can’t be bad, right? However, due to the way Windows 10 was built, you end up with two groupings of 64 threads in Task Manager, and scheduling of workloads across those groupings doesn’t always work as expected.
Video encoding doesn’t really know what to do with the 3990X. HandBrake is barely any faster with x264 encoding, and is slightly slower in x265 mode. Adobe Photoshop and Premiere Pro are both faster on a 3970X. There are numerous lighter applications where the 64-core behemoth falls well behind other CPUs—including tasks such as gaming, general Internet use, and office work.
But then you get to 3D rendering and fire up Blender with a complex scene, and suddenly all those cores are put to good use. Blender, Cinebench R20, V-Ray, POV-Ray, and Corona all have the 3990X beating the 3970X by 45-65 percent. Not surprisingly, AMD’s marketing behind the Threadripper 3990X was heavy on the Hollywood-style 3D rendering.
Now that 64-core CPUs are becoming more affordable, we should see app—and Windows— support for such chips improve as well. But there’s another problem with higher core counts: software licensing fees. Windows has already moved away from a per-socket fee to a per-core fee. VMware recently announced two tiers of pricing as well: one for up to 32 cores, and you’d buy a second license for each additional 32 cores. Oracle has been charging per core for a long time, too.
I’m not saying we’ll never need a 64-core CPU in our home PCs, but it could be decades before such systems become common. Or maybe they never will, considering the rise in smartphone use for media consumption, email, and more. Still, something has to do the heavy lifting for Hollywood, not to mention the servers behind all the smartphone networks….
Even so, I wonder what AMD has planned. Zen gave us 16core Threadripper 1950X, Zen+ delivered 32-core Threadripper 2990WX, and now Zen 2 drops a 64-core bombshell on the 3D rendering community. Will we see 128-core or even 256-core chips? Possibly, though doubling down yet again might not deliver the hoped for performance. We are well past the point of diminishing returns.