7x3070 drops speed

[sicc337]

I have 7x3070 rtx 
i7-9700k
32gb Ram
When i start hashcat i have on blowfish 7000 h/s , https://prnt.sc/1tido8b
literally in 10-15 minutes the speed drops by 1700 h/s https://prnt.sc/1tidk8q
I used Hashcat 6.2.4
I established CUDA Toolkit, drivers last version, OpenCL Runtime last version. 
https://prnt.sc/1tie6fz
https://prnt.sc/1tie7cz
How i can fix speed?

Hey!

What is the temperature of the GPUs?

Hardware.Mon.#1..: Temp: 52c Fan: 70% Util:100% Core:1919MHz Mem:6794MHz Bus:1
Hardware.Mon.#2..: Temp: 47c Fan: 70% Util:100% Core:1920MHz Mem:6794MHz Bus:1
Hardware.Mon.#3..: Temp: 46c Fan: 70% Util: 75% Core:1942MHz Mem:6794MHz Bus:1
Hardware.Mon.#4..: Temp: 45c Fan: 70% Util:  9% Core:1964MHz Mem:6794MHz Bus:1
Hardware.Mon.#5..: Temp: 48c Fan: 70% Util:  0% Core:1905MHz Mem:6794MHz Bus:1
Hardware.Mon.#6..: Temp: 53c Fan: 70% Util: 77% Core:1935MHz Mem:6794MHz Bus:1
Hardware.Mon.#7..: Temp: 45c Fan: 70% Util:  0% Core:1994MHz Mem:6794MHz Bus:1