The Intel Skylake-X Review: Core i9 7900X, i7 7820X and i7 7800X Tested
by Ian Cutress on June 19, 2017 9:01 AM ESTBenchmarking Performance: CPU Encoding Tests
One of the interesting elements on modern processors is encoding performance. This includes encryption/decryption, as well as video transcoding from one video format to another. In the encrypt/decrypt scenario, this remains pertinent to on-the-fly encryption of sensitive data - a process by which more modern devices are leaning to for software security. Video transcoding as a tool to adjust the quality, file size and resolution of a video file has boomed in recent years, such as providing the optimum video for devices before consumption, or for game streamers who are wanting to upload the output from their video camera in real-time. As we move into live 3D video, this task will only get more strenuous, and it turns out that the performance of certain algorithms is a function of the input/output of the content.
HandBrake H264 and HEVC
As mentioned above, video transcoding (both encode and decode) is a hot topic in performance metrics as more and more content is being created. First consideration is the standard in which the video is encoded, which can be lossless or lossy, trade performance for file-size, trade quality for file-size, or all of the above can increase encoding rates to help accelerate decoding rates. Alongside Google's favorite codec, VP9, there are two others that are taking hold: H264, the older codec, is practically everywhere and is designed to be optimized for 1080p video, and HEVC (or H265) that is aimed to provide the same quality as H264 but at a lower file-size (or better quality for the same size). HEVC is important as 4K is streamed over the air, meaning less bits need to be transferred for the same quality content.
Handbrake is a favored tool for transcoding, and so our test regime takes care of three areas.
Low Quality/Resolution H264: He we transcode a 640x266 H264 rip of a 2 hour film, and change the encoding from Main profile to High profile, using the very-fast preset.
More cores, more frequency, more IPC, more fun: the Core i9-7900X wins here, and even the i7-7800X wins out against the Core i7-6900K.
High Quality/Resolution H264: A similar test, but this time we take a ten-minute double 4K (3840x4320) file running at 60 Hz and transcode from Main to High, using the very-fast preset.
Moving into HQ mode means making the job more parallel, so the higher core counts stay at the top of the chart.
HEVC Test: Using the same video in HQ, we change the resolution and codec of the original video from 4K60 in H264 into 4K60 HEVC.
WinRAR 5.40
For the 2017 test suite, we move to the latest version of WinRAR in our compression test. WinRAR in some quarters is more user friendly that 7-Zip, hence its inclusion. Rather than use a benchmark mode as we did with 7-Zip, here we take a set of files representative of a generic stack (33 video files in 1.37 GB, 2834 smaller website files in 370 folders in 150 MB) of compressible and incompressible formats. The results shown are the time taken to encode the file. Due to DRAM caching, we run the test 10 times and take the average of the last five runs when the benchmark is in a steady state.
WinRAR loves having access to all the caches as much as possible, to prefetch and store data as needed. The Skylake-X chips fall back a bit here, even with DDR4-2666 support. The Core i7-7800X uses DDR4-2400 memory, so puts it further behind. Interesting didn't realise that the lower core count Broadwell-E chips were affected so much by this test, and the higher core count Ivy Bridge-E parts are faster here.
AES Encoding
Algorithms using AES coding have spread far and wide as a ubiquitous tool for encryption. Again, this is another CPU limited test, and modern CPUs have special AES pathways to accelerate their performance. We often see scaling in both frequency and cores with this benchmark. We use the latest version of TrueCrypt and run its benchmark mode over 1GB of in-DRAM data. Results shown are the GB/s average of encryption and decryption.
7-Zip
One of the freeware compression tools that offers good scaling performance between processors is 7-Zip. It runs under an open-source licence, is fast, and easy to use tool for power users. We run the benchmark mode via the command line for four loops and take the output score.
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Tephereth - Tuesday, June 20, 2017 - link
"For each of the GPUs in our testing, these games (at each resolution/setting combination) are run four times each, with outliers discarded. Average frame rates, 99th percentiles and 'Time Under x FPS' data is sorted, and the raw data is archived."So... where the hell are the games benchmarks in this review?
beck2050 - Tuesday, June 20, 2017 - link
The possibility of the 18 core beast in the upcoming Mac Pro is really exciting for music pros.That is a tremendous and long overdue leap for power users.
drajitshnew - Tuesday, June 20, 2017 - link
"... and only three PCIe 3.0 x4 drives can use the in-built PCIe RAID"I would like to know which raid level you would use. I can't see 3 m2 drives in raid 1, and raid 5 would require access to the cpu for parity calculations. Then raid 0 it is. Now, which drives will you use for raid 0, which do not saturate the DMI link for sequential reads? And if your workload does not have predominantly sequential reads, then why are you putting the drives in raid.
PeterCordes - Tuesday, June 20, 2017 - link
Standard motherboard RAID controllers are software raid anyway, where the OS drivers queue up writes to each drive separately, instead of sending the data once over the PCIe bus to a hardware RAID controller which queues writes to two drives.What makes it a "raid controller" is that you can boot from it, thanks to BIOS support. Otherwise it's not much different from Linux or Windows pure-software RAID.
If the drivers choose to implement RAID5, that can give you redundancy on 3 drives with the capacity of 2.
However, RAID5 on 3 disks is not the most efficient way. A RAID implementation can get the same redundancy by just storing two copies of every block, instead of generating parity. That avoids a ton of RAID5 performance problems, and saves CPU time. Linux md software RAID implements this as RAID10. e.g. RAID10f2 stores 2 copies of every block, striped across as many disks as you have. It works very well with 3 disks. See for example https://serverfault.com/questions/139022/explain-m...
IDK if Intel's mobo RAID controllers support anything like that or not. I don't use the BIOS to configure my RAID; I just put a boot partition on each disk separately and manage everything from within Linux. IDK if other OSes have soft-raid that supports anything similar either.
> And if your workload does not have predominantly sequential reads, then why are you putting the drives in raid.
That's a silly question. RAID0, RAID1, and RAID5 over 3 disks should all have 3x the random read throughput of a single disk, at least for high queue depths, since each disk will only see about 1/3rd of the reads. RAID0 similarly has 3x random write throughput.
RAID10n2 of 3 disks can have better random write throughput than a single disk, but RAID5 is much worse. RAID1 of course mirrors all the writes to all the disks, so it's a wash for writes. (But can still gain for mixed read and write workloads, since the reads can be distributed among the disks).
Lieutenant Tofu - Tuesday, June 20, 2017 - link
I wonder why 1600X outperforms 1800X here on WebXPRT. It's not a huge difference, but I don't see why it's happening. 6-core vs. 8-core, 3.6 GHz base, 4.0 GHz turbo. This presumably runs in just one thread, so performance should be nearly identical. The only reason I can think of is less contention across the IF on the 1600X due to less enabled cores, but don't see that having a major effect on a single-threaded test like this one.Maybe 1600X can XFR to a little higher than the 1800X.
Eyered - Tuesday, June 20, 2017 - link
Did they have any issues with heat at all?mat9v - Tuesday, June 20, 2017 - link
If that were so everyone would be using HEDT instead of 4c/8t CPUsmat9v - Tuesday, June 20, 2017 - link
Then why again why aren't every workstation consist of dual cpu xeons? If the expense is so insignificant compared to how much faster machine will earn...mat9v - Tuesday, June 20, 2017 - link
I'm just wondering how did 7900X menage to stay within 140W bracket during Prome95 tests when in other reviews it easily reached 250W or more. Is it some internal throttling mechanism that keeps CPU constantly dynamically underclocked to stay within power envelope? How does such compare to forced 4Ghz CPU clock?mat9v - Tuesday, June 20, 2017 - link
And yet in conclusion you say to play it safe and get 7900X ?How does that work together?