Re: [gentoo-user] Re: new machine : CPU : AMD FX-4100 ?

[Volker Armin Hemmann]

Am Montag, 30. Juli 2012, 10:08:24 schrieb Michael Mol:
> On Mon, Jul 30, 2012 at 2:16 AM, Nikos Chantziaras <realnc@×××××.com> wrote:
> > On 30/07/12 07:28, Michael Mol wrote:
> >> On Sun, Jul 29, 2012 at 11:55 PM, Nikos Chantziaras <realnc@×××××.com>
> >>
> >> wrote:
> >>> On 30/07/12 06:08, Michael Mol wrote:
> >>>> On Sun, Jul 29, 2012 at 10:50 PM, Nikos Chantziaras <realnc@×××××.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. 

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