hashcat gui md5 problem

[tori]

ok it's clear but why is a gtx 680 slower than a gtx 580?
a gtx 680 has a lot more cores I don't get it.

[atom]

the 580 is much higher clocked

[tori]

ok I see the shader clock is higher.
so far i had only nvidia but I thing I'm going to buy a ati 7950.