Low Power Server CPUs: the energy saving choice?
by Johan De Gelas on July 15, 2010 4:54 AM EST- Posted in
- IT Computing
Hardware Configuration
We have reviewed the Intel Xeon X5670 before: it is the best performing Intel Six-core in the 95W TDP power envelope. For comparison, we add the Intel Xeon L5640. The 32 nm “Westmere”L5640 reduces TDP to 60W, although it still has 6 cores. This chip runs at 2.26 GHz, but at lighter load it should boost itself to 2.8 GHz.
Test server
Asus RS700-E6/RS4 1U Server
Asus Z8PS-D12-1U Motherboard
Six-core Xeon L5640 2.26 GHz or Six-core Xeon X5670 2.93 GHz
6x Samsung M393B5170DZ1 - CH9 1333MHz CL9 ECC (24GB)
2x Western Digital WD1000FYPS 1TB (VM images and OS installation)
2 x Intel X25-E SLC SSD 32GB (Data Oracle OLTP & Log Oracle OLTP)
BIOS
Most Important BIOS Settings: (BIOS version 0701 (20/01/2010))
C1E Support: Enabled
Hardware Prefetcher: Enable
Adjacent Cache Line Prefetch: Enabled
Intel VT: Enabled
Active Intel SpeedStep Tech: Enabled
Intel TurboMode: Enable
Intel C-State Tech:Enabled
C3 State: ACPI C3
Software configuration:
Windows 2008 R2 Enterprise, Hyper-V enabled
vApus Mark I softwareas described here.
Current measurements
We used the racktivity PM0816-ZB datacenter PDU to measure power.
Using a PDU for accurate power measurements might same pretty insane, but this is not your average PDU. Measurement circuits of most PDUs assume that the incoming AC is a perfect sine wave, but it never is. The Rackitivity PDU measures however true RMS current and voltage at a very high sample rate: up to 20.000 measurements per seconds for the complete PDU. We read out the current and voltage out each second, which already gives us more than 4000 data points along our 70 minutes long virtualization power test. As the PDU has 8 ports, this allows us to test several servers at once, which will be very handy for future reviews.
Where is AMD’s Opteron?
We did not manage to get a decent server based on the latest AMD’s Opterons in the lab. The current “Magny-Cours” Servers in our lab are reference motherboards running in a desktop tower. So to avoid any unfair comparison with our Xeon rack servers we delay our measurements on the AMD platform until we find a way to get a real server in the lab.
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cserwin - Thursday, July 15, 2010 - link
Some props for Johan, too, maybe... nice article.JohanAnandtech - Thursday, July 15, 2010 - link
Thanks! We have more data on "low power choices", but we decided to cut them up in several article to keep it readable.DavC - Thursday, July 15, 2010 - link
not sure whats going on with your electricity cost calcs on your first page. firstly your converting current unnessacarily from watts to amps (meaning your unnessacarily splitting into US and europe figures).basically here in the UK, 1kW which is what your your 4 PCs in your example consume, costs roughly 10p per hour. working on an average of 720 hours in a month, that would give a grand total of £72 a month to run those 4 PCs 24/7.
£72 to you US guys is around $110. And I cant imagine you're electricity is priced any dearer than ours.
giving a 4 year life cycle cost of $5280.
have I missed something obvious here or are you just out with the maths?
JohanAnandtech - Thursday, July 15, 2010 - link
You are calculating from the POV of a datacenter. I take the POV of a datacenter client, which has to pay per amp that he/she "reserves". AFAIK, datacenters almost always count with amps, not Watts.(also 10p per KWh seems low)
MrSpadge - Thursday, July 15, 2010 - link
With P=V*I at constant voltage power and amps are really just a different name for the same thing, i.e. equivalent. Personally I prefer W, because this is what matters in the end: it's what I pay for and what heats my room. Amps by themselves don't mean much (as long as you're not melting the wires), as voltages can easily be converted.Maybe the datacenter guys just like to juggle around smaller numbers? Maybe the should switch over to hecto watts instead? ;)
MrS
JohanAnandtech - Thursday, July 15, 2010 - link
I am surprised the electrical engineers have not jumped in yet :-). As you indicate yourself, the circuits/wires are made for a certain amount of amps, not watts. That is probably the reason datacenters specify the amount of power you get in watt.JohanAnandtech - Thursday, July 15, 2010 - link
I meant amps in that last sentence of course.knedle - Thursday, July 15, 2010 - link
Watts are universal, doesn't matter if you're in UK, or US - 220W is still 220W, but with ampers it's different. Since in the Europe voltage is higher than in the USA (EU=220V, US=110V), and P=U*I, you've got twice as much power for 1A, which means that in USA your server will use 2A, while the same server in UK will use only 1A...has407 - Friday, July 16, 2010 - link
No, not all Watts are the same.Watts in a decent datacenter come with power distribution, cooling, UPS, etc. Those typically add 3-4x to the power your server actually consumes. Add to that the amortized cost of the infrastructure and you're looking at 6-10x the cost of the power your server consumes directly.
Such is the fallacy of simplistic power/cost comparisons (and Johan, you should know better). Can we now dispense with the idiotic cost/KWH calculations?
Penti - Saturday, July 17, 2010 - link
A high-performance server probably can't be used on 1A 230V which is the cheapest options in some datacenters. However something like half a rack or 1/4 would probably have 10A/230V, more then enough for a small servercollection of 4 moderate servers. The big cost is cooling, normal racks might handle 4kW (up to 6kW over that then it's high density) of heat/power just. Then you need more expensive stuff. A cheap rack won't handle 40 250W servers in other regards. 6 kW power/cooling and 2x16A/230V shouldn't be that expensive. Any way you also pay for cooling (and UPS). Even cheap solutions normally charge per used kW here though. 4 2U is about 1/4 rack anyway. And like 15 amps is needed if in the states.