[Discuss] Cool Processing

[Joe Polcari]

This also assumes that you have a way to adjust voltages ­ I¹ve only seen
something like that on gaming Pcs.

From:  Drew Van Zandt <drew.vanzandt at gmail.com>
Date:  Friday, June 19, 2015 at 2:52 PM
To:  "joe at polcari.com" <joe at polcari.com>
Cc:  Richard Pieri <richard.pieri at gmail.com>, "discuss at blu.org"
<discuss at blu.org>
Subject:  Re: [Discuss] Cool Processing

...and I probably left 6 other things that change out, that was just what
came to mind immediately.  :-)

Drew Van Zandt
Artisan's Asylum Board of Directors
Firefly Arts Collective Board of Directors


On Fri, Jun 19, 2015 at 2:51 PM, Joe Polcari <joe at polcari.com> wrote:
> And that¹s why. Thanks.
> 
> From:  Drew Van Zandt <drew.vanzandt at gmail.com>
> Date:  Friday, June 19, 2015 at 1:32 PM
> To:  "joe at polcari.com" <joe at polcari.com>
> Cc:  Richard Pieri <richard.pieri at gmail.com>, "discuss at blu.org"
> <discuss at blu.org>
> Subject:  Re: [Discuss] Cool Processing
> 
> You're assuming changing the voltage changes nothing else, if you try to apply
> Ohm's law directly.  Many other things change when you change the supply
> voltage of a semiconductor/PCB.
> 
> Among them:
> Switching thresholds
> Edge rates
> Leakage currents
> Capacitance of most of your capacitors
> 
> Drew Van Zandt
> Artisan's Asylum Board of Directors
> Firefly Arts Collective Board of Directors
> 
> 
> On Fri, Jun 19, 2015 at 1:26 PM, Joe Polcari <joe at polcari.com> wrote:
>> And ohm's law doesn't apply why?
>> 
>> Sent from my iPhone
>> 
>>> > On Jun 19, 2015, at 1:23 PM, Richard Pieri <richard.pieri at gmail.com>
>>> wrote:
>>> >
>>>> >> On 6/19/2015 11:02 AM, Steve Litt wrote:
>>>> >> Today I have a 16GB RAM box, with dual core CPU (I wanted things to
>>>> >> stay cool),
>>> >
>>> > I think I recently mentioned buying a new notebook. If I didn't, well I am
>>> mentioning it now: a Mythlogic-branded Clevo P750ZM. It has a Core i7-4790K
>>> processor. You read that right: a 15" notebook with a socketed Devil's
>>> Canyon i7 desktop CPU. I think I have some grounds for saying that limiting
>>> yourself to 2 cores is a poor way of managing heat.
>>> >
>>> > AMD and Intel processors draw substantially more power than they actually
>>> need. Every processor is different and the minimum stable power varies so
>>> they ship with the stock power draw set high enough that all processors in a
>>> series will run stably. Excess power turns into waste heat. This is why my
>>> i7 quickly reaches 99C under load and throttles if I don't do something
>>> about it.
>>> >
>>> > That something is called undervolting. As the name suggests it means
>>> reducing the voltage that the processor draws. Since every processor is a
>>> little different there is no single ideal undervolting setting. Finding the
>>> ideal for a given processor requires some trial and error, same as
>>> overclocking. A common starting point for Haswell i7 processors is -80mV
>>> dynamic CPU voltage offset and -100mV processor cache voltage offset. My
>>> 4790K barely reaches 80C with Intel XTU's stress test with these settings.
>>> That's the same as the i7-4790S at 3.2GHz (what the notebook originally
>>> shipped with) while running 20% faster at 4.0GHz. I figured that was good
>>> enough and called it done.
>>> >
>>> > --
>>> > Rich P.
>>> > _______________________________________________
>>> > Discuss mailing list
>>> > Discuss at blu.org
>>> > http://lists.blu.org/mailman/listinfo/discuss
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