AMD’s 16-core, 32-thread Ryzen Threadripper 1950X ($999 on Amazon) is an angry Godzilla stomping his way through downtown Tokyo. Those puny 8-core, 6-core, and 4-core CPUs? They’re just tanks and army trucks to be punted across the city.
Yes, it’s that good.
But before you buy, there’s a lot you need to know about what is arguably the most powerful consumer CPU ever unleashed upon mankind.
What is Threadripper
While Intel currently builds its CPUs around a monolithic piece of silicon for all of its cores, AMD has designed Ryzen to be modular at the chip level. The basic building block of all Ryzen CPUs are two 4-core complexes, or CCXes, joined by AMD’s high-speed Infinity Fabric interconnect. Every Ryzen 7, for example, has an 8-core die such as the one below.
To get to 16 cores in Threadripper, AMD uses the same high-speed Infinity Fabric to join two 8-core dies. The 12-core version also joins two 8-core dies, but each of the 4-core CCXs has one processor core disabled.
But wait: You’ve seen pictures of the inside of a Threadripper and there are four chips—are those two other 8-core dies just waiting to be enabled? Nope. It’s no secret that Threadripper reuses hardware from AMD’s 32-core, server-focused Epyc CPU, but AMD isn’t giving us 32-core consumer CPUs today. Two of those “chips” are actually dummy pieces to add structural support for the cooler that will be clamped onto the CPU.
With great cores, come great resources
AMD actually doubles down twice with Threadripper specs, giving you double the amount of CPU cores and double the amount of memory channels. It also vastly increases the PCIe lanes.
For example, the mainstream Ryzen line supports dual-channel DDR4 memory. Threadripper supports quad-channel DDR4. Unlike Intel, whose strategy is to disable features on its Core-series CPUs to push people to its pricier Xeon chips, AMD leaves in support for ECC RAM to help correct single-bit errors. AMD also says Threadripper should technically be able to support up to 2TB of RAM, although the company hasn’t validated this because there are no DIMMs that support the capacity yet.
As for PCIe, while the mainstream Ryzen chips offer a pedestrian 20 lanes for support of graphics cards or SSDs, Threadripper offers a whopping 64 lanes. Of those 64, four are used to connect to the south bridge, leaving 60 available to connect up to seven different simultaneous PCIe devices. That means up to four GPUs along with three NVMe PCIe drives.
Compare AMD’s generous approach to Intel’s careful rationing: The $1,000 10-core Core i9-7900X, for example, has a decent 44 lanes of PCIe, but the $599 8-core Core i7-7820X has only 28. Even AMD’s cheapest Threadripper so far, the 8-core Threadripper 1900X, features a full 64 lanes of PCIe support.
Despite many unsubstantiated rumors of a large lineup of Threadripper CPUs, AMD is officially launching only three CPUs today (the 8-core Threadripper 1900X will ship in a few more weeks). The lineup (see below) is sparser than Intel’s currently, but an unintentional leak by motherboard vendors indicates the company has lower-wattage, non-“X” versions coming, too.
Intel’s own lineup looks more impressive, but thus far, the company has shipped only the 10-core Core i9-7900X and its 8-core, 6-core, and 4-core siblings.
Installation: Read the manual. Seriously.
No matter how many systems you’ve built, if you buy Threadripper, do yourself a favor and read the manual. As expected, Threadripper brings a new CPU socket, officially called sTR4. While the mainstream Ryzen features the pin-grid array familiar with AMD fans, Threadripper moves to an LGA, or land-grid array, that will be more familiar to Intel fans.
LGA moves the delicate pins to the motherboard instead of the CPU. Which is better? From a customer point of view, it probably depends. Mash a pin on a $550 motherboard badly, and you trash the motherboard. Mash it on a $999 CPU, and you trash the CPU.
One thing we do know: Installing a Threadripper is unlike anything you’ve done before. That doesn’t mean you need to sweat bullets, but don’t just dive into it without first reading the documentation and watching a proper installation video (preferably not ours, which we did dead-tired and blind).
The three essential takeaways from your manual-reading and video-watching should be these:
- You must keep the plastic orange carrier on the CPU. The CPU can’t be installed without it.
- You must use the torque wrench that’s packed into the bottom of the Threadripper box (see above).
- Pay attention to the correct sequence for installing and uninstalling the CPU.
To install it, you open the socket by loosening three T20 Torx screws with the AMD-provided wrench. Remove the top-level protective plate and insert the entire CPU with the orange plastic carrier. Slide the CPU until it clicks into place or is clearly at the bottom of the assembly.
Once you’re sure the CPU is in the carrier correctly, remove the protective cover over the socket and gently lower the CPU into place. Finally, you carefully tighten all three Torx screws with the provided AMD torque wrench.
One more time: Don’t try to muddle through this without at least familiarizing yourself with the process.
Meet the new Game Mode
Before we get to the all-important performance section, you should know about Threadripper’s new Gaming Mode. Most people don’t buy 16-core CPUs to play video games, but the world is a-changing, and many professional gamers and streamers need the ability to play games at high frame rates and also edit the content once it’s done.
When it designed Threadripper, AMD says it realized the high-thread-count CPU didn’t always perform at its best for some games. Remember, it’s made using two separate chips, each with its own dual-channel memory controller. Out of the box, Threadripper supports Uniform Memory Access mode, which spreads the memory access between both memory controllers. The benefit is greater memory bandwidth, but often higher latency. Some games, AMD says, just want low latency.
To address this, AMD has introduced a new Game Mode that switches the system to Non-Uniform Memory Access (NUMA), or what AMD calls Local Mode. Local Mode essentially shunts all memory access to one memory controller to lower latency. Memory access that goes to the other memory controller is possible, but it’s done with higher latency.
Threadripper’s crazy core count has another unintended consequence: AMD says some older games crashed in its tests. This isn’t a problem with Threadripper, AMD notes, but the games themselves, because they just can’t handle the number of CPU cores.
To address this problem, Game Mode essentially tells Windows to recognize only 8 of the 16 CPUs in the system. An updated Ryzen Master Utility lets you switch between Game Mode when it’s needed for older games, and Creator Mode when you want all of your CPU cores and more memory bandwidth.
Does it work? Yes. Although we won’t get into its impact on gaming until later, we did measure the modes’ impact on latency and memory bandwidth. You can see how Game Mode lowers memory latency in the chart above.
As you can see in the next chart, however, Game Mode has the opposite effect on memory bandwidth. Because Game Mode enables NUMA/Local Mode, you give up a significant amount of memory bandwidth
What’s right? Well, it’s complicated. Gears of War Ultimate, AMD says, likes low memory latency, so Game Mode should be on for that game. Rise of the Tomb Raider likes more CPU cores, so maybe you’ll want it off. Far Cry 4 likes low core-to-core latency, so maybe you’ll want to switch on Game Mode.
If this all sounds way too complicated when you just want to play a game, know that for the most part this is just being nit-picky. Any modern game paired with a modern powerful GPU and a Threadripper CPU will run fine at normal resolutions and visual quality settings. AMD just wants gamers to have more granular control so they can wring more performance out of the new CPU. Some may be put off by this complexity, but if you’re really buying a 16-core, 32-thread CPU just for conventional gaming, you’re doing it wrong. A regular Ryzen or Kaby Lake CPU is probably better for that purpose.
Time for performance numbers! Keep reading.
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