dict attack with GPU

[bobva]

i try to crack a truecrypt file that i know the password is a 3 word from a big list (16000 word (dict.dict)) and i have a 3 GPU

i write a command:
cudahashcat64.exe -a 7 -m 6211 c:\file.tc ?a?a?a dict.dict

the hachcat start and the program run only in 1 GPU. and the other GPU dont work.
how can i run in the other GPU to?

[atom]

you need to pipe:

https://hashcat.net/wiki/doku.php?id=fre...e_all_gpus

[bobva]

you need to pipe:

https://hashcat.net/wiki/doku.php?id=fre...e_all_gpus

what i need to write?
this?

?a?a?a dict.dict | cudahashcat64.exe -a 7 -m 6211 c:\file.tc

[atom]

$ mp64 ?a?a?a -o aaa.txt

$ combinator aaa.txt dict.dict | cudahashcat64.exe -m 6211 c:\file.tc