The AMD Ryzen Threadripper 1950X and 1920X Review: CPUs on Steroids
by Ian Cutress on August 10, 2017 9:00 AM ESTFeeding the Beast
When frequency was all that mattered for CPUs, the main problem became efficiency, thermal performance, and yields: the higher the frequency was pushed, the more voltage needed, the further outside the peak efficiency window the CPU was, and the more power it consumed per unit work. For the CPU that was to sit at the top of the product stack as the performance halo part, it didn’t particularly matter – until the chip hit 90C+ on a regular basis.
Now with the Core Wars, the challenges are different. When there was only one core, making data available to that core through caches and DRAM was a relatively easy task. With 6, 8, 10, 12 and 16 cores, a major bottleneck suddenly becomes the ability to make sure each core has enough data to work continuously, rather than waiting at idle for data to get through. This is not an easy task: each processor now needs a fast way of communicating to each other core, and to the main memory. This is known within the industry as feeding the beast.
Top Trumps: 60 PCIe Lanes vs 44 PCIe lanes
After playing the underdog for so long, AMD has been pushing the specifications of its new processors as one of the big selling points (among others). Whereas Ryzen 7 only had 16 PCIe lanes, competing in part against CPUs from Intel that had 28/44 PCIe lanes, Threadripper will have access to 60 lanes for PCIe add-in cards. In some places this might be referred to as 64 lanes, however four of those lanes are reserved for the X399 chipset. At $799 and $999, this competes against the 44 PCIe lanes on Intel’s Core i9-7900X at $999.
The goal of having so many PCIe lanes is to support the sort of market these processors are addressing: high-performance prosumers. These are users that run multiple GPUs, multiple PCIe storage devices, need high-end networking, high-end storage, and as many other features as you can fit through PCIe. The end result is that we are likely to see motherboards earmark 32 or 48 of these lanes for PCIe slots (x16/x16, x8/x8/x8/x8, x16/x16/x16, x16/x8/x16/x8), followed by a two or three for PCIe 3.0 x4 storage via U.2 drives or M.2 drives, then faster Ethernet (5 Gbit, 10 Gbit). AMD allows each of the PCIe root complexes on the CPU, which are x16 each, to be bifurcated down to x1 as needed, for a maximum of 7 devices. The 4 PCIe lanes going to the chipset will also support several PCIe 3.0 and PCIe 2.0 lanes for SATA or USB controllers.
Intel’s strategy is different, allowing 44 lanes into x16/x16/x8 (40 lanes) or x16/x8/x16/x8 (40 lanes) or x16/x16 to x8/x8/x8x8 (32 lanes) with 4-12 lanes left over for PCIe storage or faster Ethernet controllers or Thunderbolt 3. The Skylake-X chipset then has an additional 24 PCIe lanes for SATA controllers, gigabit Ethernet controllers, SATA controllers and USB controllers.
Top Trumps: DRAM and ECC
One of Intel’s common product segmentations is that if a customer wants a high core count processor with ECC memory, they have to buy a Xeon. Typically Xeons will support a fixed memory speed depending on the number of channels populated (1 DIMM per channel at DDR4-2666, 2 DIMMs per channel at DDR4-2400), as well as ECC and RDIMM technologies. However, the consumer HEDT platforms for Broadwell-E and Skylake-X will not support these and use UDIMM Non-ECC only.
AMD is supporting ECC on their Threadripper processors, giving customers sixteen cores with ECC. However, these have to be UDIMMs only, but do support DRAM overclocking in order to boost the speed of the internal Infinity Fabric. AMD has officially stated that the Threadripper CPUs can support up to 1 TB of DRAM, although on close inspection it requires 128GB UDIMMs, which max out at 16GB currently. Intel currently lists a 128GB limit for Skylake-X, based on 16GB UDIMMs.
Both processors run quad-channel memory at DDR4-2666 (1DPC) and DDR4-2400 (2DPC).
Top Trumps: Cache
Both AMD and Intel use private L2 caches for each core, then have a victim L3 cache before leading to main memory. A victim cache is a cache that obtains data when it is evicted from the cache underneath it, and cannot pre-fetch data. But the size of those caches and how AMD/Intel has the cores interact with them is different.
AMD uses 512 KB of L2 cache per core, leading to an 8 MB of L3 victim cache per core complex of four cores. In a 16-core Threadripper, there are four core complexes, leading to a total of 32 MB of L3 cache, however each core can only access the data found in its local L3. In order to access the L3 of a different complex, this requires additional time and snooping. As a result there can be different latencies based on where the data is in other L3 caches compared to a local cache.
Intel’s Skylake-X uses 1MB of L2 cache per core, leading to a higher hit-rate in the L2, and uses 1.375MB of L3 victim cache per core. This L3 cache has associated tags and the mesh topology used to communicate between the cores means that like AMD there is still time and latency associated with snooping other caches, however the latency is somewhat homogenized by the design. Nonetheless, this is different to the Broadwell-E cache structure, that had 256 KB of L2 and 2.5 MB of L3 per core, both inclusive caches.
Facebook
Twitter
RSS
347 Comments
View All Comments
BOBOSTRUMF - Friday, August 11, 2017 - link
Actually Intel's 140 can consume more than 210 if You want the top unrestricted performance limited. Read tomshardware reviewFiliprino - Thursday, August 10, 2017 - link
How comes WinRAR is faster with the 10 core Broadwell than with the 10 core Skylake?What did they change on Cinebench going from 10 to 11.5? Threadripper is the faster CPU in Cinebench 10, but in the newer one it is not. Then again Cinebench 15 shows TR as the faster CPU. Is this benchmark reliable?
How comes Chromium compilation is so slow? Others have pointed out they get much better scaling (linear speedup). That makes sense because compilation basically consists in launching isolated processes (compiler instances). Is this related with the segfaulting problem under GNU/Linux systems?
For encoding I would start to use FFmpeg when benchmarking so many cores. In my brain lies a memory of FFmpeg being faster than Handbrake for the same number of cores. Maybe the GUI loop interrupts the process in a performance-unfriendly way. Too much overhead. HPC workloads can suffer even from the network driver having too many interrupts (hence, Linux tickless configuration).
I have read SYSMARK Results and I find strange that TR media results are slower than data, being TR slower than Intel in media and faster than Intel in data. Isn't SYSMARK from BAPCo (http://www.pcworld.com/article/3023373/hardware/am... You already point it out on the article, sorry.
How comes R9 Fury in Shadow of Mordor has AMD and Intel CPUs running consistently at two different frame rates (~95 vs ~103)?
The same but with the GTX 1080. Both cases happen regardless of the Intel architecture (Haswell, Broadwell and Skylake all have the same FPS value).
What happens with NVIDIA driver on Rocket League? Bad caching algorithm (TR has more cores/threads -> more cache available to store GPU command data)? You say you had issues but, what are your thoughts?
How comes GTA V has those Under 60 and 30 FPS graphs knowing that the game is available for PS4 and XBox One (it has been already optimized for two CCX CPU, at least there is a version for that case)? Nevertheless, with NVIDIA cards, 2 seconds out of 90 is not that much.
What I can think is that all these benchmarks are programmed using threading libraries from the "good old times" due to bad scaling. And in some cases there is architecture-specific targeted code. I also include in my conception the small dataset being used. I also would not make a case out of a benchmark programmed with code having false sharing (¡:O!)
Currently for gaming, it seems that the easiest way is to have a Virtual Machine with PCIe passthrough pinned to one of the MCM dies.
As a suggestion to Anandtech, I would like to see more free (libre) software being used to measure CPU performance, compiling the benchmarks from source against the target CPU architecture. Something like Phoronix. Maybe you could use PTS (Phoronix Test Suite).
Filiprino - Thursday, August 10, 2017 - link
Positive things: ThreadRipper is under its TDP consumption. Intel is more power hungry. The Intel 16-core might go through the rough in power consumption.Good gaming performance. Intel is generally better, but TR still offers a beefy CPU for that too, losing a few frames only.
Strong rendering performance.
Strong video encoding performance.
When you talk about IPC, it would be useful to measure it with profiling tools, not just getting "points", "miliseconds" and "seconds".
Seeing how these benchmarks do not scale by much beyond 10 cores you might realize software has to get better.
Chad - Thursday, August 10, 2017 - link
Second ffmpeg test (pretty please!)mapesdhs - Thursday, August 10, 2017 - link
Ian, a query about the CPU Legacy Tests: why do you reckon does the 1920X beat both 1950X and 1950X-G for CB 11.5 MT, yet the latter win out for CB 10 MT? Is there a max-thread limit in V11.5? Filiprino asked much the same above.
"...and so losing half the threads in Game Mode might actually be a detriment to a workstation implementation."
Isn't that the whole point though? For most workstation tasks, don't use Game Mode. There will be exceptions of course, but in general...
Btw, where's C-ray? ;)
Ian.
Da W - Thursday, August 10, 2017 - link
ALL OF YOU COMPLAINERS: START A TECH REVIEW WEBSITE YOURSELVES AND STFU!hansmuff - Thursday, August 10, 2017 - link
Don't read the comments. Also, a lot of the "complaints" are read by Ryan and he actually addresses them and his articles improve as a result of criticism. He's never been bad, but you can see an ascension in quality over time, along with his partaking in critical commentary.IOW, we don't really need a referee.
hansmuff - Thursday, August 10, 2017 - link
And of course I mean Ian, not Ryan.mapesdhs - Friday, August 11, 2017 - link
It is great that he replies at all, and does so to quite a lot of the posts too.Kepe - Thursday, August 10, 2017 - link
Wait a second, according to AMD and all the other articles about the 1950X and Game Mode, game mode disables all the physical cores of one of the CPU clusters and leaves SMT on, so you get 8 cores and 16 threads. It doesn't just turn off SMT for a 16 core / 16 thread setup.AMD's info here: https://community.amd.com/community/gaming/blog/20...