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Date: Sun, 26 May 2019 20:33:36 -0700
From: Eric Oyen <>
Subject: Re: exact performance of supported ztex board for
 WPA/PSK cracking

One of the issues I have here is high in-house temperatures during the summer. I live in a house with 1960’s quality insulation and uses only an evaporations cooler. I have had to take to using a small cube fridge to keep my Mac mini cool. This would also work for any GPU outboard cards if housed in a mini-ATX type case. However, your mileage may vary depending on your computer case and other factors.


> On May 25, 2019, at 8:27 AM, Solar Designer <> wrote:
> On Fri, May 24, 2019 at 06:28:32PM +0200, Johny Krekan wrote:
>> Thanx for information, so for cracking WPA PSK can John use other than GPU 
>> acceleration if yes what devices?
> For practical purposes, it is just GPUs and CPUs.  Theoretically, it is
> also any other devices for which you have an OpenCL backend.
>> GPUs are very temperature-intensive.
> You can underclock GPUs or reduce their power limit (where supported),
> or with our latest release (or bleeding-jumbo) you can also set a
> maximum temperature that JtR will try not to exceed by adjusting the
> duty cycle.  Of course, this hurts performance.  From the NEWS file and
> the release announcement:
> - Graceful handling of GPU overheating - rather than terminate the process,
>  JtR will now optionally (and by default) sleep until the temperature is below
>  the limit, thereby adjusting the duty cycle to keep the temperature around
>  the limit.  (Applies to NVIDIA and old AMD drivers.  We do not yet have GPU
>  temperature monitoring for new AMD drivers.)  [Claudio, Solar; 2019]
> The corresponding john.conf settings are:
> # Abort the process or sleep for a while if a GPU hits this temperature (in C)
> AbortTemperature = 95
> # Instead of aborting, sleep for this many seconds to cool the GPU down when
> # the temperature hits the AbortTemperature value, then re-test the temperature
> # and either wake up or go to sleep again.  Set this to 0 to actually abort.
> # Suppress repeated sleep/wakeup messages when SleepOnTemperature = 1,
> # we are interpreting this as intent to keep the GPU temperature around the limit.
> SleepOnTemperature = 1
> So you just change the 95 to a lower value according to your preference.
> Alexander

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