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.
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PixyMisa - Tuesday, July 11, 2017 - link
No, the pricing is correct. The 1P CPUs really are half the price of a single 2P CPU.msroadkill612 - Wednesday, July 12, 2017 - link
Seems to me, the simplest explanation of something complex, is to list what it will not do, which they will not do :(.Can i run a 1p Epyc in a 2p mobo e.g., please?
PixyMisa - Thursday, July 13, 2017 - link
Short answer is no. It might boot, but only half the slots, memory, SATA and so on will be available. Two 1P CPUs won't talk to each other.A 2P Epyc will work in a 1P board though.
cekim - Tuesday, July 11, 2017 - link
One glaring bug/feature of AMD's segmentation relative to Intel's is the utter and obvious crippling of clock speeds for all but the absolute top SKUs. Fewer cores should be able to make use of higher clocks within the same TDP envelope. As a result Intel is objectively offering more and better fits up and down the sweep of cores vs clocks vs price spectrum.So, the bottom line is AMD is saying that you will have to buy the top-end, 4S SKU to get the top GHz for those applications in your mix that won't benefit from 16,18,32,128 cores.
I say all of this as someone who desperately wants EPYC to shake things up and force Intel to remove the sand-bags. I know I'm in a small, but non-zero market of users who can make use of dozens of cores, but still need 8 or fewer cores to perform on par with desktop parts for that purpose.
KAlmquist - Wednesday, July 12, 2017 - link
One possibility is that they have only a small percentage of the chips currently being produced bin well enough to be used in the highest clocking SKU's, so they are saving those chips for the most expensive offerings. Admittedly, that depends on what they are seeing coming off the production line. If they have a fair number of chips where with two very good cores, and two not so good, then it would make sense to offer a high clocking 16 core EPYC using chips with two cores disabled. But if clock speed on most chips is limited due to minor registration errors (which would affect the entire chip), then a chip with only two really good cores would require two localized defects in two separate cores, in addition to very good registration to get the two good cores. The combination might be too rare to justify a separate SKU.I would expect Global Foundries to continue to tweak its process to get better yields. In that case, more processors would end up in the highest bin, and AMD might decide to launch a higher clock speed 16 and 8 core EPYC processors, mostly using chips which bin well enough that they could have been used for the 32 core EPYC 7601.
alpha754293 - Tuesday, July 11, 2017 - link
Why does the Intel Xeon 6142 cost LESS than the 6142M? (e.g. per the table above, 6142 is shown with a price of $5946 while the 6142M costs $2949)ca197 - Tuesday, July 11, 2017 - link
I assume that is the wrong way round on the list. I have seen it reported the other way round on other sites.Ian Cutress - Tuesday, July 11, 2017 - link
You're correct. I've updated the piece, was a misread error from Intel's tables.coder543 - Tuesday, July 11, 2017 - link
On page 6, it says that Epyc only has 64 PCIe lanes (available), but that's not correct. There are 128 PCIe lanes per chip. In a 1P configuration, that's 128 PCIe lanes available. On a 2P configuration, 64 PCIe lanes from each chip are used to connect to the other chip, leaving 64 + 64 = 128 PCIe lanes still available.This is a significant advantage.
Ian Cutress - Tuesday, July 11, 2017 - link
You misread that table. It's quoting per-CPU when in a 2P configuration.