Low utilization with multi GPU

As stated, I recently upgraded my cracking rig from 1-1080Ti to 2x1080TI + 3x1070Ti taking advantage of the cheap GPU's with the mining exodus. The issue is, I have the 2x1080Ti's on water, when I only had1 gpu performance was great in hashcat, gpu was 100% utilized and rates were 630Mh/s+ (wpa2) (As this was also my display gpu). After adding the rest of them, and in no matter what order I run them in ( using -d 1,2 for example) each GPU will only get to about 36% utilization and the performance therefore is terrible. Is there an easy fix for this I am missing?

I will add that I have tweaked the cards , power and clock rate etc via afterburner (currently in windows, will test results in linux today as well) and using the benchmark feature (-b) they all put out great numbers, but when using in practice its down to ~36% utilization .. see benchmark below

OpenCL Platform #1: NVIDIA Corporation
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* Device #1: GeForce GTX 1080 Ti, 2816/11264 MB allocatable, 28MCU
* Device #2: GeForce GTX 1080 Ti, 2816/11264 MB allocatable, 28MCU
* Device #3: GeForce GTX 1070 Ti, 2048/8192 MB allocatable, 19MCU
* Device #4: GeForce GTX 1070 Ti, 2048/8192 MB allocatable, 19MCU

Benchmark relevant options:
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* --optimized-kernel-enable

Hashmode: 2500 - WPA-EAPOL-PBKDF2 (Iterations: 4096)

Speed.Dev.#1.....:   663.8 kH/s (84.77ms) @ Accel:128 Loops:64 Thr:1024 Vec:1
Speed.Dev.#2.....:   626.5 kH/s (44.77ms) @ Accel:128 Loops:32 Thr:1024 Vec:1
Speed.Dev.#3.....:   439.0 kH/s (87.31ms) @ Accel:128 Loops:64 Thr:1024 Vec:1
Speed.Dev.#4.....:   459.6 kH/s (83.42ms) @ Accel:128 Loops:64 Thr:1024 Vec:1
Speed.Dev.#*.....:  2188.9 kH/s