This is me killin it on Ubuntu 16.04 w/ 6x MSI rx470 4GB
[14:31:16] Thread 3, GPU ID 3, GPU Type: Ellesmere: 635.87H/s
[14:31:16] Thread 2, GPU ID 2, GPU Type: Ellesmere: 634.97H/s
[14:31:17] Thread 5, GPU ID 5, GPU Type: Ellesmere: 641.74H/s
[14:31:18] Thread 1, GPU ID 1, GPU Type: Ellesmere: 644.15H/s
[14:31:18] Thread 4, GPU ID 4, GPU Type: Ellesmere: 641.23H/s
[14:31:18] Thread 0, GPU ID 0, GPU Type: Ellesmere: 641.01H/s
[14:31:18] Share accepted: 72/72 (100.00%)
[14:31:18] Total Hashrate: 3838.97H/s
BONUS --> Only 640w total draw at the wall... (custom bios 1160core/1900mem/1500straps)
How are you modifying your bios? You just going into UEFI boot and changing the options? I'm new to this obviously.
Core 1160 = gpu core clock rate?
Mem = memclock rate?
What is straps?
Also, have you tried undervolting the gpu's or is it possible on ubuntu?
I have 2 unmodded sapphire rx480's running at 577H/s
"threads": 1,
"rawintensity": 1024,
"worksize": 8
currently getting about 627h/s out of twin xfx 8gb 480s without modding bios on them, however i did OC my CPU/RAM. you can tinker with those settings to find optimal speed/voltage/heat ratio that works best for your hardware.