AMD's 12-core "Magny-Cours" Opteron 6174 vs. Intel's 6-core Xeon
by Johan De Gelas on March 29, 2010 12:00 AM EST- Posted in
- IT Computing
Power Consumption
The Magny-Cours Opteron arrived one week ago, which is barely enough time to do virtualization benchmarking. So we have to postpone extensive power testing to a later date. The Opteron 6174 came in a desktop reference system which is in no way comparable to our Xeon X5670 1U server. We do have an six-core Opteron based system which is very similar to the Opteron 6174 reference system: the motherboard is also equipped with the new AMD SR5670 chipset and housed in the same desktop system. We can tell you that the idle power of the Opteron 6174 is a few watts lower than the six-core Opteron 2435. Both throttle back to 800 MHz, but the Opteron 6100 series gets a real C1E mode.
C1E mode can only be entered if all CPUs are idle. In a dual socket system, both CPUs enter C1E or they don’t. C1E mode is entered only after longer periods of inactivity. All cores flush their L1 and L2 caches to the L3-cache. Then all cores are clockgated (C1). Once that happens, the Hyper Transport links are put in a lower power state. This allows the chipset to enter a lower power state as well. Only when all these previous steps are done, both sockets are in C1E. DMA events will make the sockets go out of the C1E state. So C1E probably won't happen much on server systems. The C1E state is only entered if absolutely no processing is happening at all.
The C1E mode can reduce power quite a bit:
- Core clocks are turned off (Clockgate C1 state)
- L3, North Bridge, and memory controller all divide their clock frequencies (but are not clockgated!)
- All HyperTranspor links transition to LS2 low power state (LDT_STOP_L)
- DRAM DLL’s disabled
- Memory Transitions from precharge power down mode to self refresh mode (low power)
According to AMD, at full load a 1.7GHz 65W ACP Opteron 6164 HEwould consume about 4% more power than a 2.1 GHz 55W ACP 6-core Opteron 2425 HE. AMD measured 225W for the former, 215W for the latter. We measured 263W on the same system at full load with an Opteron 6174. That's 48W more, or about 24W per CPU. Assuming that the low power CPUs were running at their ACP (65W), we can conclude that the 2.2 GHz Magny-Cours needs about 89W. While the new twelve-core Opteron clearly needs a bit more power than the six-core Opteron, it's not a dramatic increase.
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Accord99 - Monday, March 29, 2010 - link
The X5670 is 6-core.JackPack - Tuesday, March 30, 2010 - link
LOL. Based on price?Sorry, but you do realize that the majority of these 6-core SKUs will be sold to customers where the CPU represents a small fraction of the system cost?
We're talking $40,000 to $60,000 for a chassis and four fully loaded blades. A couple hundred dollars difference for the processor means nothing. What's important is the performance and the RAS features.
JohanAnandtech - Tuesday, March 30, 2010 - link
Good post. Indeed, many enthusiast don't fully understand how it works in the IT world. Some parts of the market are very price sensitive and will look at a few hundreds of dollars more (like HPC, rendering, webhosting), as the price per server is low. A large part of the market won't care at all. If you are paying $30K for a software license, you are not going to notice a few hundred dollars on the CPUs.Sahrin - Tuesday, March 30, 2010 - link
If that's true, then why did you benchmark the slower parts at all? If it only matters in HPC, then why test it in database? Why would the IDM's spend time and money binning CPU's?Responding with "Product differentiation and IDM/OEM price spreads" simply means that it *does* matter from a price perspetive.
rbbot - Saturday, July 10, 2010 - link
Because those of us with applications running on older machines need comparisons against older systems in order to determine whether it is worth migrating existing applications to a new platform. Personally, I'd like to see more comparisons to even older kit in the 2-3 year range that more people will be upgrading from.Calin - Monday, March 29, 2010 - link
Some programs were licensed by physical processor chips, others were licensed by logical cores. Is this still correct, and if so, could you explain in based on the software used for benchmarking?AmdInside - Monday, March 29, 2010 - link
Can we get any Photoshop benchmarks?JohanAnandtech - Monday, March 29, 2010 - link
I have to check, but I doubt that besides a very exotic operation anything is going to scale beyond 4-8 cores. These CPUs are not made for Photoshop IMHO.AssBall - Tuesday, March 30, 2010 - link
Not sure why you would be running photoshop on a high end server.Nockeln - Tuesday, March 30, 2010 - link
I would recommend trying to apply some advanced filters on a 200+ GB file.Especially with the new higher megapixel cameras I could easilly see how some proffesionals would fork up the cash if this reduces the time they have to spend in front of the screen waiting on things to process.