Sizing Up Servers: Intel's Skylake-SP Xeon versus AMD's EPYC 7000 - The Server CPU Battle of the Decade?
by Johan De Gelas & Ian Cutress on July 11, 2017 12:15 PM EST- Posted in
- CPUs
- AMD
- Intel
- Xeon
- Enterprise
- Skylake
- Zen
- Naples
- Skylake-SP
- EPYC
AMD’s EPYC 7000-Series Processors
As announced back at the official launch, AMD is planning to hit both the dual socket and single socket markets. With up to 32 cores, 64 threads, 2TB/socket support and 128 PCIe lanes per CPU, they believe that by offering a range of core counts and frequencies, they have the nous to attack Intel, even if it comes at a slight IPC disadvantage.
AMD’s main focus will be on the 2P parts, where each CPU will use 64 PCIe lanes (using the Infinity Fabric protocol) to connect to each other, meaning that in a 2P system there will still be 128 PCIe 3.0 lanes to go around for add-in devices. There will be the top four SKUs available initially, and the other parts should be in the hands of OEMs by the end of July. All the CPUs will have access to all 64MB of the L3 cache, except the 7200-series which will have access to half.
The new processors from AMD are called the EPYC 7000 series, with names such as EPYC 7301 and EPYC 7551P. The naming of the CPUs is as follows:
EPYC 7551P
- EPYC = Brand
- 7 = 7000 Series
- 30/55 = Dual Digit Number indicative of stack positioning / performance (non-linear)
- 1 = Generation
- P = Single Socket, not present in Dual Socket
So in the future, we will see second generation ‘EPYC 7302’ processors, or if AMD scales out the design there may be EPYC 5000 processors with fewer silicon dies inside, or EPYC 3000 with a single die but for the EPYC platform socket (obviously, those last two are speculation).
But starting with the 2P processors:
| AMD EPYC Processors (2P) | |||||||||
| Cores Threads |
Frequency (GHz) | L3 | DRAM | PCIe | TDP | Price | |||
| Base | All | Max | |||||||
| EPYC 7601 | 32 / 64 | 2.20 | 2.70 | 3.2 | 64 MB | 8-Ch DDR4 2666 MT/s |
8 x16 128 PCIe |
180W | $4200 |
| EPYC 7551 | 32 / 64 | 2.00 | 2.55 | 3.0 | 180W | >$3400 | |||
| EPYC 7501 | 32 / 64 | 2.00 | 2.60 | 3.0 | 155W/170W | $3400 | |||
| EPYC 7451 | 24 / 48 | 2.30 | 2.90 | 3.2 | 180W | >$2400 | |||
| EPYC 7401 | 24 / 48 | 2.00 | 2.80 | 3.0 | 155W/170W | $1850 | |||
| EPYC 7351 | 16 / 32 | 2.40 | 2.9 | 155W/170W | >$1100 | ||||
| EPYC 7301 | 16 / 32 | 2.20 | 2.7 | 155W/170W | >$800 | ||||
| EPYC 7281 | 16 / 32 | 2.10 | 2.7 | 32 MB | 155W/170W | $650 | |||
| EPYC 7251 | 8 / 16 | 2.10 | 2.9 | 120W | $475 | ||||
The top part is the EPYC 7601, which is the CPU we were provided for in this comparison. This is a 32-core part with simultaneous multithreading, a TDP of 180W and a tray price of $4200. As the halo part, it also gets the good choice on frequencies: 2.20 GHz base, 3.2 GHz at max turbo (up to 12 cores active) and 2.70 GHz when all cores are active.
Moving down the stack, AMD will offer 24, 16 and 8-core parts. These will disable 1, 2 and 3 cores per CCX respectively, as we saw with the consumer Ryzen processors, and is done in order to keep core-to-core latencies more predictable (as well as keeping access to all the L3 cache). What is interesting to note is that AMD will offer a 32-core part at 155W (when using DDR4-2400) for $3400, which is expected to be very competitive compared to Intel (and support 2.66x more DRAM per CPU).
The 16-core EPYC 7281, while having half the L3, will be available for $650, making an interesting 2P option. Even the bottom processor at the stack, the 8-core EPYC 7251, will support the full 2TB of DRAM per socket as well as 128 PCIe lanes, making it a more memory focused SKU and having almost zero competition on these sorts of builds from Intel. For software that requires a lot of memory but pays license fees per core/socket, this is a nice part.
For single socket systems, AMD will offer the following three processors:
| AMD EPYC Processors (1P) | |||||||||
| Cores Threads |
Frequency (GHz) | L3 | DRAM | PCIe | TDP | Price | |||
| Base | All | Max | |||||||
| EPYC 7551P | 32 / 64 | 2.0 | 2.6 | 3.0 | 64 MB | 8-Ch DDR4 2666 MT/s |
8 x16 128 PCIe |
180W | $2100 |
| EPYC 7401P | 24 / 48 | 2.0 | 2.8 | 3.0 | 155W/170W | $1075 | |||
| EPYC 7351P | 16 / 32 | 2.4 | 2.9 | 155W/170W | $750 | ||||
These processors mirror the specifications of the 2P counterparts, but have a P in the name and slightly different pricing.
Facebook
Twitter
RSS
219 Comments
View All Comments
oldlaptop - Thursday, July 13, 2017 - link
Why on earth is gcc -Ofast being used to mimic "real-world", non-"aggressively optimized"(!) conditions? This is in fact the *most* aggressive optimization setting available; it is very sensitive to the exact program being compiled at best, and generates bloated (low priority on code size) and/or buggy code at worst (possibly even harming performance if the generated code is so big as to harm cache coherency). Most real-world software will be built with -O2 or possibly -Os. I can't help but wonder why questions weren't asked when SPEC complained about this unwisely aggressive optimization setting...peevee - Thursday, July 13, 2017 - link
"added a second full-blown 512 bit AVX-512 unit. "Do you mean "added second 256 ALU, which in combination with the first one implements full 512-bit AVX-512 unit"?
peevee - Thursday, July 13, 2017 - link
"getting data from the right top node to the bottom left node – should demand around 13 cycles. And before you get too concerned with that number, keep in mind that it compares very favorably with any off die communication that has to happen between different dies in (AMD's) Multi Chip Module (MCM), with the Skylake-SP's latency being around one-tenth of EPYC's."1/10th? Asking data from L3 on the chip next to it will take 130 (or even 65 if they are talking about averages) cycles? Does not sound realistic, you can request data from RAM at similar latencies already.
AmericasCup - Friday, July 14, 2017 - link
'For enterprises with a small infrastructure crew and server hardware on premise, spending time on hardware tuning is not an option most of the time.'Conversely, our small crew shop has been tuning AMD (selected for scalar floating point operations performance) for years. The experience and familiarity makes switching less attractive.
Also, you did all this in one week for AMD and two weeks for Intel? Did you ever sleep? KUDOS!
JohanAnandtech - Friday, July 21, 2017 - link
Thanks for appreciating the effort. Luckily, I got some help from Ian on Tuesday. :-)AntonErtl - Friday, July 14, 2017 - link
According to http://www.anandtech.com/show/10158/the-intel-xeon... if you execute just one AVX256 instruction on one core, this slows down the clocks of all E5v4 cores on the same socket for at least 1ms. Somewhere I read that newer Xeons only slow down the core that executes the AVX256 instruction. I expect that it works the same way for AVX512, and yes, this means that if you don't have a load with a heavy proportion of SIMD instructions, you are better off with AVX128 or SSE. The AMD variant of having only 128-bit FPUs and no clock slowdown looks better balanced to me. It might not win Linpack benchmark competitions, but for that one uses GPUs anyway these days.wagoo - Sunday, July 16, 2017 - link
Typo on the CLOSING THOUGHTS page: "dual Silver Xeon solutions" (dual socket)Great read though, thanks! Can finally replace my dual socket shanghai opteron home server soon :)
Chaser - Sunday, July 16, 2017 - link
AMD's CPU future is looking very promising!bongey - Tuesday, July 18, 2017 - link
EPYC power consumption is just wrong. Somehow you are 50W over what everyone else is getting at idle. https://www.servethehome.com/amd-epyc-7601-dual-so...Nenad - Thursday, July 20, 2017 - link
Interesting SPECint2006 results:- Intel in their slide #9 claims that Intel 8160 is 2% faster than EPYC 7601
- Anandtech in article tests that EPYC 7601 is 42% faster than Intel 8176
Those two are quite different, even if we ignore that 8176 should be faster than 8160. In other words, those Intel test results look very suspicious.