help plz :ERROR: Temperature limit

hi

I used hashcat from along time It,s amazing but It take a long time

then I bought a new PC to use oclhashcat

my new PC
CPU : intel Core i5 4670k
MB : Asrock Z87 extreme4
GPU : GIGABYTE HD 7970 GHz
HDD : WD Blue 1TB
RAM : Kingston Hayperx 8GB
PSU : Corsair GS800
and i have 6 fans in my case
but I have this problem ERROR: Temperature limit on GPU 1 reached, aborting...

when i use this command
-a 3 -m 0 xxx.txt ?a?a?a?a?a

can you help me to use a new command like it can solve the Temperature

like slowly command or something can solve my problem

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How do I control the speed of decoding؟
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I don't have experience in oclhashcat and my english language is not very well

thanx alot