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Full Version: Low GPU load for dictionary attack
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Hello,
I have two hashing rigs, running on Ubuntu 14.04 LTS. Rig #1 has 4x Gigabyte R9 280x GPUs, Rig #2 has 4x MSI Twinfrozr III 7950 GPUs.

I use latest version of oclHashcat + hashtopus.

When I use mask brute force attack mode amdconfig shows continuous 99% load on every card, but for dictionary mode it drops to 70-95% and fluctuates.

Dictionary is quite big, 36 GB plain text, so I thought it's because hard drive. However I've been monitoring my hard drive (3 TB Seagate Barracuda 7200rpm) and I couldn't find any bottlenecks. During normal operation reading from drive takes maybe 5% of full speed, IOPS is on 30-50% level.

CPU is also good, 30-50% load.

It happens for both of my rigs.

So how comes it doesn't use full speed of my cards if there are no bottlenecks?

Well, at least I don't see them.

Any ideas?
You're not giving the GPU enough work to do. It is impossible to gain any acceleration with straight dictionary attacks against fast hashes unless you supply an amplifier.

http://hashcat.net/wiki/doku.php?id=freq...full_speed