most energy efficient CPU out there?

joolz · Post by **joolz** » Thu Dec 14, 2006 5:39 am

Hi,

What is the most energy efficient CPU money can buy? Except the ITX-cpu:s. Is a standard core 2 more efficient then an AMD 35W cpu? Is Pentium M still a good choice? Im just interested in "new" processors.

thanks!

jojo4u · Post by **jojo4u** » Thu Dec 14, 2006 5:59 am

CPU is one side, platform another. Please specify more what kind of work your cpu is intended to do.

joolz · Post by **joolz** » Thu Dec 14, 2006 6:51 am

im going to build a mATX system, it will just act as a fileserver/router/firewall etc. Its going to be on 24/7 and i want it to make as little noise as possible.

my old p3 is going to be replaced with this one as its starting to show its age.

dnoiz · Post by **dnoiz** » Thu Dec 14, 2006 7:00 am

I think AMD has some CPU's that will make you happy. Example : Athlon 64 X2 3800+ (64-bit, Energy Efficient, 2.0GHz, 1MB total dedicated L2 cache, 2000MHz HyperTransport bus) - comes at 35W. That's probalby AM2 socket.

Look around on Google and you'll surely will find what you need.

R.

joolz · Post by **joolz** » Thu Dec 14, 2006 7:12 am

ok, so this CPU require less sauce then a Pentium M or core 2 duo for example?

nici · Post by **nici** » Thu Dec 14, 2006 7:26 am

Which pentium M? If its an LV or ULV model it only comsumes a few watts. If its a normal PM or CD/C2D it comsumes more than AMD in idle, and less in load. Or something. But answering your first question, a Pentium M UltraLowVoltage would probably be it.

You can easily cool a 35W CPU passiely with a large heatsink like a Ninja. In fileserver/router/firewall work it probably wont even consume half of that. Pretty much any modern cpu, een the slowest models, are much faster than needed for that stuff.

You should worry more about HDDs than the CPU, a moderataley cool CPU is easy to cool very quietly, HDDs are a major pain in the bum. Especially sideways.

jojo4u · Post by **jojo4u** » Thu Dec 14, 2006 8:27 am

Well since you P3 is not fast enough any more we need > 1 GHz I think. So Epia is out of question, as well as Geode.
SPCR desktop survey: http://www.silentpcreview.com/article313-page1.html

Since it is 24/7 you need low idle power consumption. This rules out desktop Core 2 Duo.

all watt figures idle
1. A Pentium-M or Yonah laptop with Intel IGP. With display off < 10W from battery possible + psu loss (brick efficiency!). I have some figures from battery available. Gigabyte ethernet is not widespread.

2. Abit iL-90MV + Core Solo 20 W from wall viewtopic.php?t=35472&highlight=abit

3. AOpen i945GTt-VFA with Yonah 22 W from wall http://www.silentpcreview.com/article701-page9.html

4. AM2 board with Athlon 64: ~30W viewtopic.php?p=304441#304441. This report is amazingly low, but 44 W have been measured by someone else: viewtopic.php?p=300802. Also 31W here viewtopic.php?p=268055#268055

PEG is needs much power, try to avoid it. PSU should be Seasonic SFX or PicoPSU/PW-200. Ask yourself wether Gigabyte Ethernet is necessary. 2.5" hdd need 1W idle, 3.5" min 5W.

Edit: 5. Socket 754 board with Sempron or Turion. This should, in theorie give very low figures at a bargain price. I haven't digged into this topic so I can't give you a starting point here. SPCR Turion on the desktop viewtopic.php?p=268055#268055

jaganath · Post by **jaganath** » Thu Dec 14, 2006 10:02 am

Edit: 5. Socket 754 board with Sempron or Turion. This should, in theorie give very low figures at a bargain price

Yes, but avoid E6 Sempron with 1.1V Vcore lock. 2500,2800 don't have Vcore lock.

jojo4u · Post by **jojo4u** » Thu Dec 14, 2006 11:37 am

More info about the 1.1V locking:
viewtopic.php?t=34083

joolz · Post by **joolz** » Sat Dec 16, 2006 4:33 am

Thanks very much for the input. Im going with a mb that has a Gigabyte Ethernet, because im going to have my /home/ or part of it on this server. Im also going to use 3.5 disk because i require quite a lot of space.

The "Yonah" processor, where can i find it? What architecture is it.

also, i was thinking a FAN less ATX CPU, like the silverstone, cause the mATX case im going for a chassi that supports regular size PSU,
http://www.lian-li.com/Product/Chassis/ ... C-V300.htm

Aris · Post by **Aris** » Sat Dec 16, 2006 6:48 am

Im currently running a Pentium-M 1.73 system right now. I can run it completely passively with a large tower heatpipe cooler. However, a 5volted 120mm nexus fan is completely inaudible, and the cooling performance increase is HUGE over just convection or internal case airflow. So there really is no reason to run a cpu completely fanless.

dhanson865 · Post by **dhanson865** » Sat Dec 16, 2006 9:29 am

These are F2 stepping 90nm chips you could get right now. But if you get a motherboard that would run these you could upgrade to a G stepping 65nm chip next year.

Or if you are willing to wait you can research AM2 boards now and get a low wattage 65nm chip when it is announced next year and skip the 90nm chips.

Code: Select all

OPN (Tray)      OPN_PIB           Processor Model        Frequency   Socket   Wattage
ADD3500IAA4CN   ADD3500CNBOX      AMD Athlonâ„¢ 64 3500+    2200Mhz      AM2      35W
ADD3800IAT5CU   ADD3800CUBOX      AMD Athlonâ„¢ 64 X2 3800+ 2000Mhz      AM2      35W
SDD3500IAA2CN   SDD3500CBNOX      AMD Sempronâ„¢  3500+     2000Mhz      AM2      35W
SDD3400IAA3CN   SDD3400CBNOX      AMD Sempronâ„¢  3400+     1800Mhz      AM2      35W
SDD3200IAA2CN   SDD3200CNBOX      AMD Sempronâ„¢  3200+     1800Mhz      AM2      35W
SDD3000IAA3CN   SDD3000CNBOX      AMD Sempronâ„¢  3000+     1600Mhz      AM2      35W

joolz · Post by **joolz** » Sat Dec 16, 2006 9:59 am

So will the new 65nm cpus require even less than 35W ?

Le_Gritche · Post by **Le_Gritche** » Sat Dec 16, 2006 10:27 am

jojo4u wrote:Since it is 24/7 you need low idle power consumption. This rules out desktop Core 2 Duo.

That piece of shared knowledge will have to change, as Intel is introducing in December Core 2 Duo E6300, E6400, E6600 and E6700 with a revised "Extended HALT", meaning a lower sleep state, at 12W instead of the current 20-22W.
That's according to hardware.fr, in "Les Core 2 Duo moins gourmands", Intel's own PCN (Product Change Notification) being their source.

That was one of the last advantages of AMD over Intel in the desktop market, now, apart from the price...

pyogenes · Post by **pyogenes** » Sat Dec 16, 2006 10:28 am

joolz wrote:So will the new 65nm cpus require even less than 35W ?

The current 65nm AMD released are rated at 65W TDP and no low power model has been announced yet (they aren't even shipping retail boxed versions yet).

jaganath · Post by **jaganath** » Sat Dec 16, 2006 11:23 am

That piece of shared knowledge will have to change, as Intel is introducing in December Core 2 Duo E6300, E6400, E6600 and E6700 with a revised "Extended HALT", meaning a lower sleep state, at 12W instead of the current 20-22W.
...That was one of the last advantages of AMD over Intel in the desktop market, now, apart from the price...

Not so fast...what is the relationship between the "sleep state" and idle? AFAIK idle and sleep are two very different states.

Le_Gritche · Post by **Le_Gritche** » Sat Dec 16, 2006 12:21 pm

jaganath wrote:Not so fast...what is the relationship between the "sleep state" and idle? AFAIK idle and sleep are two very different states.

My fault sorry, "sleep state" were my words and indeed can be confusing as they generally refer to the OS state, and not the processor state.
According to Intel website the confusion remains somewhat though :

# Save on energy-consumption with Enhanced Intel SpeedStepÂ® TechnologyÂ² when combined with existing power saving features, providing power when you need it while conserving it when you don't
# Lower frequency and voltage when Enhanced Halt StateÂ² is activated putting the operating system into idle mode which helps reduce power consumption

(I pulled that from a Pentium D feature description page )

I'm not at all familiar with Intel's processors, so maybe someone else can confirm or infirm it, but judging from that it seems SpeedStep would be the feature shutting down certain parts of the processor, while Enhanced Halt (sometimes referred to as C1E I think) is the feature close to Cool'n'Quiet, underclocking and undervolting the whole processor.

EDIT: googling a bit, I found an article on AnandTech discussing the differences between Enhanced Halt State (C1E) and SpeedStep (EIST), I have to say the more I read, the less I am able to say what each feature does exactly. Apparently from that article, C1E would be a lower idle state than conventionaly allowed by SpeedStep.

joolz · Post by **joolz** » Sat Dec 16, 2006 12:48 pm

interesting. i think i will go for AM2 SFF system. Does anyone have a mATX mobo to recommend? Power efficient, gb lan, integrated graphics, sata 3Gb/s.

Le_Gritche · Post by **Le_Gritche** » Sat Dec 16, 2006 1:22 pm

joolz wrote:interesting. i think i will go for AM2 SFF system. Does anyone have a mATX mobo to recommend? Power efficient, gb lan, integrated graphics, sata 3Gb/s.

SPCR's recommended motherboards topic lists only two AM2 mATX mobo, with integrated graphics, those are the Asus M2NPV-VM and Abit NF-M2 nView. LAN and SATA characteristics are not mentionned.

vincentfox · Post by **vincentfox** » Sat Dec 16, 2006 6:25 pm

Back up to original step please, and define what you mean by "fileserver/router/firewall". What kind of load do you have, and what kind of performance are you looking for? For example it makes no sense to have a single-user with gigabit ethernet, talking to a very slow storage device.

Quite a lot of firewall/router systems run off very low-power CPU. You can do this part of the job in 10 Watts or less. Well assuming you are talking about a residential connection and not a corporate network.

Fileserver is a different matter. Depends on how much you want it to do. You can get some very minimalist embedded NAS devices. In many ways it makes more sense to have this function on a separate device INSIDE your LAN instead of having it on the router/firewall.

Stereodude · Post by **Stereodude** » Sat Dec 16, 2006 8:14 pm

There's a Ultra Low Voltage 9W Core 2 Duo. That's probably the highest performance per watt chip.

pyogenes · Post by **pyogenes** » Sat Dec 16, 2006 8:40 pm

Stereodude wrote:There's a Ultra Low Voltage 9W Core 2 Duo. That's probably the highest performance per watt chip.

Yeah, but not really worth considering unless you're willing to buy it soldered on a motherboard (assuming you can even find a vendor to buy it from).

Stereodude · Post by **Stereodude** » Sun Dec 17, 2006 7:28 am

pyogenes wrote:Yeah, but not really worth considering unless you're willing to buy it soldered on a motherboard (assuming you can even find a vendor to buy it from).

Hey, I never said it was practical.

joolz · Post by **joolz** » Sun Dec 17, 2006 8:27 am

vincentfox wrote:Back up to original step please, and define what you mean by "fileserver/router/firewall". What kind of load do you have, and what kind of performance are you looking for? For example it makes no sense to have a single-user with gigabit ethernet, talking to a very slow storage device.

By fileserver i mean i will store almost all my data on this device, my entire /home/ (i run linux) will be mounted from the server, and as im hitting the roof on my 100mbit connection, i want to go for gigabit, of course i don't expect to get x10 performance, but at least double it. Im also going to run a small ftp on it, 100mbit connection to the Internet. And maybe encrypt my hdd with 256 AES. So i think ill need some juice.

jojo4u · Post by **jojo4u** » Sun Dec 17, 2006 10:28 am

Le_Gritche wrote:, I have to say the more I read, the less I am able to say what each feature does exactly. Apparently from that article, C1E would be a lower idle state than conventionaly allowed by SpeedStep.

viewtopic.php?t=36560 would be a good place to discuss this topic. You can ask what is still unclear to you there, and i'll try explain it.

vincentfox · Post by **vincentfox** » Sun Dec 17, 2006 12:37 pm

Wow, what ISP offers 100 megabit service?

joolz · Post by **joolz** » Sun Dec 17, 2006 1:00 pm

vincentfox wrote:Wow, what ISP offers 100 megabit service?

BBB (Bredbandsbolaget), in Sweden.

dhanson865 · Post by **dhanson865** » Mon Dec 18, 2006 1:52 pm

joolz wrote:So will the new 65nm cpus require even less than 35W ?

Answer A: no chip uses exactly 35W. It is just a design point for the heatsink manufacturers to consider. You may pay for a 35W TDP and get a 10W TDP part or you may pay for 35W TDP and get 30+W TDP. The guarantee is that it won't exceed 35W.

Answer B: The 65nm parts that will be low TDP may or may not be 35W TDP. Even if they are the key factor is that they should have lower voltages per clock frequency or said another way they should be able to clock higher at the same power usage as the 90nm parts.

We won't know exactly how they will compare until they are released but I'm expecting them to beat the core 2 duo for power use at idle more so than they do now.

For an idea of how it is now and a hint of things to come (I could quote a number of other articles but this was the first hit on Google):

http://www.extremetech.com/article2/0,1 ... 252,00.asp
AMD: New Chips Consume Half the Power of Core 2 Duo

AMD's sales team is also attempting to convince customers that even its older "Rev. F" 65-watt, 90nm chips actually consume less power than Intel's Core 2 Duo components, with the delta even more magnified when its new 35-watt, 65nm chips are compared.

AMD's argument goes like this: Modern desktop and notebook processors constantly scale up and down between full speed and an idle state, which AMD has branded "Cool 'n' Quiet". At a given time, pushed to full load by an application, AMD's chips run hotter and consume more power. But across a typical computing dayâ€”where a user might check his email or surf the Webâ€”the processor idles more often then not. At idle, AMD's 90nm Athlon 64 X2 consumes 7.5 watts. A 35-watt, 65-nm chip will idle at 3.8 watts, AMD said. By comparison, the 65nm Core 2 Duo idles at 14.3 watts.

AMD's 90nm/65 watt Athlon 64 X2 chips consumed 47.6 percent the power of a 65nm Core 2 Duo chip, the company said. A 35-watt X2 consumes 73.3 percent of the power of the same Core 2 Duo. However, directly comparing the two chips' power load in a real-world computing environment, over the course of a day, would be a daunting task, Huynh acknowledged.

Note that the TDP at idle numbers indicate the actual wattage at idle, and the % numbers equal the % of TDP (the theoretical max). Also note that the processors AMD announced at 65-watt TDP, not 35-watt. The 35-watt numbers are for apparently forthcoming products.

AMD Athlon 64 X2 65W TDP at idle: 7.5W

% of 65W TDP: 11.5%

AMD Athlon 64 X2 35W TDP at idle: 3.8W

% of 35W TDP: 10.9%

Intel Core 2 Duo 65W TDP at idle: 14.3 W

% of 65W TDP: 22.0%

In AMD tests:

â€“ AMD Athlonâ„¢ 64 X2 65W TDP desktop processor idle power was 47.6% less than Intel Core 2 Duo 65W TDP processor power

â€“ AMD Athlonâ„¢ 64 X2 35W TDP desktop processor idle power was 73.3% less than Intel Core 2 Duo 65W TDP processor power

The reason I didn't quote these numbers in my first message in this thread is that you may not be sitting at idle most of the time. If you are at idle most of the day then you are better off with even the 90nm 65W TDP parts.

If you are at load most of the day it is a wash between the low end Core 2 Duo and performance equivalent 90nm 65W TDP Athlon X2.

But next year the new low power 65nm Athlon X2 will be all the rage on these boards (at least that is my prediction based on the numbers I've read).

aristide1 · Post by **aristide1** » Thu Dec 21, 2006 5:41 pm

But next year the new low power 65nm Athlon X2 will be all the rage on these boards (at least that is my prediction based on the numbers I've read).

Keep this in mind,

http://www.anandtech.com/cpuchipsets/sh ... spx?i=2893

of course things will change later.

dhanson865 · Post by **dhanson865** » Sun Dec 24, 2006 8:00 am

Yes, keep in mind that RAM sensitive applications will notice a difference when the K8 core is set to a half multiplier. You may see better performance at 11x than you do at 11.5x in some applications.

Of course if you are undervolting or spending most of your time at IDLE then that small performance loss won't matter.

If you are overclocking and disabling cool n quiet then you can force an integer multiplier while you are at it.

The L2 cache latency is a non issue as far as I'm concerned.

Or you could even do something crazy like undervolt/underclock your CPU but overclock the RAM (by motherboard standards). It isn't terribly uncommon to see RAM sold at higher rated speeds than the default settings in the BIOS such as DDR433, 466, and 500 when DDR400 is the "normal" speed.