FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Gentoo > Gentoo User

 
 
LinkBack Thread Tools
 
Old 07-30-2012, 04:45 PM
Volker Armin Hemmann
 
Default new machine : CPU : AMD FX-4100 ?

Am Montag, 30. Juli 2012, 10:08:24 schrieb Michael Mol:
> On Mon, Jul 30, 2012 at 2:16 AM, Nikos Chantziaras <realnc@gmail.com> wrote:
> > On 30/07/12 07:28, Michael Mol wrote:
> >> On Sun, Jul 29, 2012 at 11:55 PM, Nikos Chantziaras <realnc@gmail.com>
> >>
> >> wrote:
> >>> On 30/07/12 06:08, Michael Mol wrote:
> >>>> On Sun, Jul 29, 2012 at 10:50 PM, Nikos Chantziaras <realnc@gmail.com>
> >>>>
> >>>> wrote:
> >>>>> On 30/07/12 05:23, Philip Webb wrote:
> >>>>>> i5-2550K & FX-4100 both use 95 W
> >>>>>> (some of the more costly AMDs use 125 W ).
> >>>>>
> >>>>> Note that power savings are not important if you're not using a
> >>>>> laptop.
> >>>>> CPU
> >>>>> power savings on a desktop don't translate to any relevant amount of
> >>>>> money
> >>>>> on your electricity bills. This is because neither of those CPUs
> >>>>> really
> >>>>> use
> >>>>> 95W. That's just the thermal upper limit.
> >>>>
> >>>> To be fair, power savings are relevant if you're concerned about your
> >>>> electric bill, or if you're concerned about heat management in your
> >>>> system.
> >>>>
> >>>> Consider my dual E5345...leaving that on 24x7 appears to cost me about
> >>>> 90USD/mo.
> >>>
> >>> CPU power savings will transform that into a 89.9USD/mo ;-) That's what
> >>> I
> >>> mean. It's not worth much. It helps quite a bit with laptop battery
> >>> life.
> >>> But for desktops, it doesn't do anything too useful.
> >>
> >> If you really want the hard numbers, check out some place like Tom's
> >> Hardware or Phoronix. I forget which does the power consumption
> >> measurements. At some of the hardware review blogs, you can get
> >> numbers on idle vs full-load power consumption, as measured at the
> >> wall. The difference truly is striking.
> >
> > When you have full load, the CPU won't clock down. So nothing saved
> > there.
>
> When you're considering full load, the TDP becomes a useful estimation
> of relative power consumption between different processors.
>
> > If you don't have full load, the clock-down doesn't save much compared to
> > max clocks while idle.
>
> This is where you're wrong.
>
> http://www.tomshardware.com/reviews/ivy-bridge-benchmark-core-i7-3770k,3181-
> 23.html
>
> http://www.tomshardware.com/reviews/fx-power-consumption-efficiency,3060-11.
> html

I wouldn't trust anything Tom's publishes.

That said, Intel's 'TDP' is not really a 'TDP' - for almost a decade Intel's
'TDP' is not the 'real' TDP but a 'usually you won't get higher than this' -
until you run some really heavy stuff. Like compiling openoffice...

AMD followed suit some time ago. So both numbers are misleading at best.

That said, idle&low load consumption is fine with all CPU's. Mobos and PSUs
influence that numbers a lot more.

--
#163933
 
Old 07-30-2012, 05:00 PM
Michael Mol
 
Default new machine : CPU : AMD FX-4100 ?

On Mon, Jul 30, 2012 at 12:36 PM, James <wireless@tampabay.rr.com> wrote:
>
>
>> > When you have full load, the CPU won't clock down. So nothing saved there.
>
>> When you're considering full load, the TDP becomes a useful estimation
>> of relative power consumption between different processors.
>
>> > If you don't have full load, the clock-down doesn't save much compared to
>> > max clocks while idle.
>
>> This is where you're wrong.
>
> OK. both sides are well stated.
>
> Amp meters are less than $50 USD. They clamp around the
> power cord, or any wires inside the computer you can fit
> the "clamp" around.
>
> So make your choice, based on actual measurements?
> That's how an EE would make a decision on how
> a given processor or software setup actually effects
> the power consumption. REAL DATA.
>
> Note, some of the fancier meter's have an integrator function
> where measurements are taken frequently over a time period
> to get an even more realistic picture of power consumption...
>
> http://www.allaboutcircuits.com/vol_6/chpt_2/4.html

I've got a Kill-o-Watt which I use for these kinds of purposes.

The problem with obtaining first-hand data for a purchasing decision
is getting the parts to perform the tests on.

--
:wq
 
Old 07-30-2012, 05:04 PM
Mark Knecht
 
Default new machine : CPU : AMD FX-4100 ?

On Mon, Jul 30, 2012 at 9:36 AM, James <wireless@tampabay.rr.com> wrote:
<SNIP>
>
> Amp meters are less than $50 USD. They clamp around the
> power cord, or any wires inside the computer you can fit
> the "clamp" around.

<SNIP>
>
> hth,
> James
>
>
I haven't read this thread but I do use one of these which costs less than $20:

http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=pd_sim_hi_1

Personally I think CPU power consumption is a red herring without
including the power consumed by the rest of the box:

MB power?
Hard drive power?
Hard disk power
GPU power?
DRAM power?

The 5 above can easily become the dominant power hogs.

I use an Intel i7 980X 6-core hyper-threaded CPU, so that's 12 CPUs in
top, which burns _lots_ of power, but I suspect it's not the biggest
power consumer when compared to the total of the 6 500GB 7200 RPM hard
drives I have in the box.

WRT to money spent to run a machine I hope someone stated earlier than
this that it's the whole system that matters and not just the CPU.

Cheers,
Mark
 
Old 07-30-2012, 05:14 PM
Michael Mol
 
Default new machine : CPU : AMD FX-4100 ?

On Mon, Jul 30, 2012 at 1:04 PM, Mark Knecht <markknecht@gmail.com> wrote:
> On Mon, Jul 30, 2012 at 9:36 AM, James <wireless@tampabay.rr.com> wrote:
> <SNIP>
>>
>> Amp meters are less than $50 USD. They clamp around the
>> power cord, or any wires inside the computer you can fit
>> the "clamp" around.
>
> <SNIP>
>>
>> hth,
>> James
>>
>>
> I haven't read this thread but I do use one of these which costs less than $20:
>
> http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=pd_sim_hi_1
>
> Personally I think CPU power consumption is a red herring without
> including the power consumed by the rest of the box:
>
> MB power?
> Hard drive power?
> Hard disk power
> GPU power?
> DRAM power?
>
> The 5 above can easily become the dominant power hogs.
>
> I use an Intel i7 980X 6-core hyper-threaded CPU, so that's 12 CPUs in
> top, which burns _lots_ of power, but I suspect it's not the biggest
> power consumer when compared to the total of the 6 500GB 7200 RPM hard
> drives I have in the box.

Spinning disks consume surprisingly little power once they're up to
speed. My GPU, by comparison, doesn't seem to reduce heat generation
very much when relatively idle.

>
> WRT to money spent to run a machine I hope someone stated earlier than
> this that it's the whole system that matters and not just the CPU.

I didn't state so explicitly, no, but I believe I mentioned the two
machines had been otherwise comparable in their equipment loadout. If
I missed that, my bad.

--
:wq
 
Old 07-30-2012, 06:06 PM
Mark Knecht
 
Default new machine : CPU : AMD FX-4100 ?

On Mon, Jul 30, 2012 at 10:14 AM, Michael Mol <mikemol@gmail.com> wrote:
> On Mon, Jul 30, 2012 at 1:04 PM, Mark Knecht <markknecht@gmail.com> wrote:
<SNIP>
>>
>> MB power?
>> Hard drive power?
>> Hard disk power
>> GPU power?
>> DRAM power?
>>
>> The 5 above can easily become the dominant power hogs.
>>
>> I use an Intel i7 980X 6-core hyper-threaded CPU, so that's 12 CPUs in
>> top, which burns _lots_ of power, but I suspect it's not the biggest
>> power consumer when compared to the total of the 6 500GB 7200 RPM hard
>> drives I have in the box.
>
> Spinning disks consume surprisingly little power once they're up to
> speed. My GPU, by comparison, doesn't seem to reduce heat generation
> very much when relatively idle.
>

OK, point taken about the disks at least when talking about a single
disk. I see we measure the same way with a Kill-a-Watt so that's at
least consistent.

And I think we're in more or less violent agreement, but reducing the
CPU power in the end won't save all that much on the electric bill, or
so I think.

I ran around really quickly to find some spec values for the machine
I'm on right now. No idea if the numbers are right. They are just what
I found quickly:

CPU - i7-980x - 130W

vs

Asus Rampage II Extreme - Can't find so far, so let's guess 25W for
the chipset, NICS, audio devices, etc.
WD RAID Edition 500GB - 8W * 6 = 48W
NVidia GTX 465 class card = 80W
24GB DRAM - Total guess, but about 1W/DIMM looks safe, so 6W total

So a __really__ rough guess is my machine should use about (130 + 25 +
48 + 80 + 6) Watts, or 289W assuming I added it up correctly. That's
under full load though. My UPS has a power meter in it. The UPS is
driving this machine, 3 monitors, a small switch, a wireless access
point and maybe one or two other small things I've forgotten or have
plugged in somewhere. When the machine is essentially idle that mater
reads 330W. When I start a VM that uses 6 processor cores and runs for
30 minutes at full tilt the power consumption is 385W. I no longer
remember what I have set up in terms of the CPU clocking stuff. It's
on the machine and let's the box go full tilt, but I'm not sure what
it does when the machine is idle.

Anyway, if you assume that the 55W jump was the difference between the
980x idling, and then using 3 cores full tilt, then 6 cores (12
threads) might be more like a 100W jump which seems about right
according to Intel's spec.

In terms of the electric bill, don't forget the PC power supply is
only 80-90% efficient, so 10-20% is thrown away there also.

Now, assume you get a CPU that draws half the power. This setup would
still likely draw something close to 330W when it's idling, and might
only jump up by 60W when running full tilt. That would save maybe
(330+60)/(330+100) or only about 10% on the whole system power
consumption. For that reason I don't think skimping on the CPU makes
much sense to me. I'll happily turn the box off 2 hours a day vs go
slower all the time, but that's just me.

>>
>> WRT to money spent to run a machine I hope someone stated earlier than
>> this that it's the whole system that matters and not just the CPU.
>
> I didn't state so explicitly, no, but I believe I mentioned the two
> machines had been otherwise comparable in their equipment loadout. If
> I missed that, my bad.

And I don't know that you did as I haven't read the thread, but part
of my argument is that you have to know the WHOLE system and not just
the CPU to decide if changing the CPU costs or saves much power.

Cheers,
Mark
 
Old 07-30-2012, 06:12 PM
Michael Hampicke
 
Default new machine : CPU : AMD FX-4100 ?

Am 30.07.2012 19:14, schrieb Michael Mol:
> On Mon, Jul 30, 2012 at 1:04 PM, Mark Knecht <markknecht@gmail.com> wrote:
>> On Mon, Jul 30, 2012 at 9:36 AM, James <wireless@tampabay.rr.com> wrote:
>> <SNIP>
>>>
>>> Amp meters are less than $50 USD. They clamp around the
>>> power cord, or any wires inside the computer you can fit
>>> the "clamp" around.
>>
>> <SNIP>
>>>
>>> hth,
>>> James
>>>
>>>
>> I haven't read this thread but I do use one of these which costs less than $20:
>>
>> http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=pd_sim_hi_1
>>
>> Personally I think CPU power consumption is a red herring without
>> including the power consumed by the rest of the box:
>>
>> MB power?
>> Hard drive power?
>> Hard disk power
>> GPU power?
>> DRAM power?
>>
>> The 5 above can easily become the dominant power hogs.
>>
>> I use an Intel i7 980X 6-core hyper-threaded CPU, so that's 12 CPUs in
>> top, which burns _lots_ of power, but I suspect it's not the biggest
>> power consumer when compared to the total of the 6 500GB 7200 RPM hard
>> drives I have in the box.
>
> Spinning disks consume surprisingly little power once they're up to
> speed. My GPU, by comparison, doesn't seem to reduce heat generation
> very much when relatively idle.
>

When I built my NAS box I did meassure the power consumption of my box,
first with one HD, then two, three and so one. And I figured that one of
my (Samsung) HDs uses about 5 Watts when running idle.
 
Old 07-30-2012, 06:27 PM
Mark Knecht
 
Default new machine : CPU : AMD FX-4100 ?

On Mon, Jul 30, 2012 at 11:12 AM, Michael Hampicke <gentoo-user@hadt.biz> wrote:
<SNIP>
>> Spinning disks consume surprisingly little power once they're up to
>> speed. My GPU, by comparison, doesn't seem to reduce heat generation
>> very much when relatively idle.
>>

Idle on a GPU (in Linux) might be more when the screen is black. I
don't even know how to drive my GPU hard. It's just not part of my
life here. Maybe certain games or something?

>
> When I built my NAS box I did meassure the power consumption of my box,
> first with one HD, then two, three and so one. And I figured that one of
> my (Samsung) HDs uses about 5 Watts when running idle.
>

That's very consistent with the WD numbers I found. Something like 6W
idle, 8W max, etc. for my RAID Edition drives which are not WD Green
drives which likely have lower numbers.

Point is that there's little power saved in a box with 6 drives going
from max use to idle, etc. But I know you know that! :-)

Anyway, we're getting similar results is what it sounds like to me.

- Mark
 

Thread Tools




All times are GMT. The time now is 09:22 PM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org