Boosting hashcat performance with YouTube

[illyria]

Inspired by epixoip's tweet earlier today, I decided to spend a few minutes documenting my own similar experience.

I never previously reported this,  as A) I found a work around, B) the problem was very sporadic and C) never saw anyone else with similar reports, and figured something in my setup was wonky.

System setup:
Windows 10
CPU: A8 5500
RAM: 16GB
GPU: GTX1070
Hashcat: 3.0.0 through 3.5.0
Nvidia drivers: 368.xx through 381.xx

The original discussion referenced in the tweet mentions Minecraft as the instigator, but my experiences has it working with both YouTube and MPC-HC, ie. anything that offloads work to the GPU

First let's look at MSI Afterburner monitor outputs:




A] Starting up hashcat

Code:

-m 0 -a 0 -w 3 ?b?b?b?b?b?b?b

letting the GPU warm up


B] GPU has reached temp limit, and is hashing away at 13.3 GH/s



C] Opening browser and navigating to https://youtu.be
Presto! Speed jumped to 14.6 GH/s

Notice how GPU usage stabilises at close to 100% and power consumption is less flaky
NB! No need to playback any videos or even load a specific video, just loading the front page will do the trick. Same with MPC-HC just load the video and pause it.



D] Closing browser, and everything returns to "normal".

As I mentioned in the beginning this behaviour is very sporadic. After a reboot, I may see normal behaviour and have GPU utilisation at 100%, only to see it 3 hours into a hash-cracking run switch to the more irratic behaviour documented above.

And for those wondering why Power usage sits at 50%, I will refer you to hashcat's tweet and accompanying Google Docs spreadsheet on performance vs power consumption.

50% power limit: 14,600 MH/s @84W = 173 MH/s/W
100% power limit: 17,300 MH/s @148W = 117 MH/s/W

For the record, similar behaviour is exhibited with the power limit set to 100%.