The latest video card generation that is manufactured by ATI and Nvidia can be used to speed up password recovery attempts tremendously. Toolkits like Nvidia’s CUDA offer drivers and development examples to aid developer’s in the integration of gpu accelerated password recovery programs. One of the programs that is making use of the gpu to recover passwords is Rar GPU Password Recovery. The supported video cards at this point in time are ATI HD RV7×0s cards that include ATI Radeon 4870, 4890 and 4770 or Nvidia cards supported CUDA including GTX 260, 8600 GTS or 8600 GT. It is also recommended to have the latest Catalyst or Geforce drivers installed.

The developer provides some plain numbers to show the effectiveness of using the GPU to recover a rar password with four characters:

* ~168 passwords per second on single core of Q6600 @ 2.4Ghz
* ~325 passwords per second on 8600 GT
* ~3120 passwords per second on ATI HD4850
* ~2075 passwords per second on GTX260/192SP

The performance of the listed ATI card is almost 20 times that of a password recovery where only the cpu is used. The password recovery software is a command line utility and the developer is offering extensive information on the possible parameters that can be used to recover the password. The suggested length of the password should not exceed six characters although it is theoretically possible to start a password recovery for a password with up to 17 chars.
http://www.golubev.com/rargpu.htm