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Date: Thu, 30 Apr 2020 21:42:04 +0100
From: Darren Wise <>
Subject: Re: Reduce CPU load. Is it possible?

I actually utilise an ASRock Intel H110 Pro BTC+ board but you can now purchase boards with CPU built in these days and for fairly very little and outfit them with GPUs if needed, quite bulky mind you and you'll need to assemble a frame to support the cards nicely but it is all standard DIY.

My first had seven GTX770 GPU cards each on a PCIe single lane basis but needed more for scientific compute so 2~4U enterprise is more to my liking, cracking/hashing however they are fine for if you need other food for thought.

Windows can sometimes be a bit funny when adding all the boards at once and installing so I'd suggest installing one each time and rebooting, then adding another each time. UNIX/POSIX, Linux whatever does not seem to mind so much.

On 30 April 2020 20:03:50 BST, Solar Designer <> wrote:
>On Thu, Apr 30, 2020 at 07:16:49PM +0200, MA40 wrote:
>> Now, he also has John the Ripper running trying to decrypt some
>> hashes.
>For those, ideally you'd use GPUs.  More importantly though, you'd
>the attack based on what you recall about the password(s).
>> Of course I am interested in maximum power, but I do not want to
>reduce the
>> life of the processor, it is working without too many expectations of
>> obtaining any result with John the Ripper.
>> That is why I wanted to offload the CPU work a bit. (80% would be
>You may use OMP_NUM_THREADS like I described to make JtR use a subset
>your CPU's cores, thereby reducing its heat dissipation.
>Darren's suggestion to use "cpulimit" would likely result in efficiency
>loss as it'd mess with OpenMP thread synchronization.
>I think you never mentioned what OS you're running JtR on.

Sent from my Android device with K-9 Mail. Please excuse my brevity.

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