[Discuss] Cool Processing

[Drew Van Zandt]

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

*Drew Van ZandtArtisan's Asylum Board of DirectorsFirefly Arts Collective
Board of Directors*

On Fri, Jun 19, 2015 at 2:51 PM, Joe Polcari <joe at polcari.com> wrote:

> And that’s 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 ZandtArtisan's Asylum Board of DirectorsFirefly 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
>> _______________________________________________
>> Discuss mailing list
>> Discuss at blu.org
>> http://lists.blu.org/mailman/listinfo/discuss
>>
>
>