After the 3 day in town delivery UPS finally get you 
May I can try helping
May I can try helping
Dear Martin,
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So i tried your boards with hexmine in win7, tried all the combinations got 42gh with one board, 77ghs with two, 91gh with three, 101gh with foor
it's little wired why its slowing down when you add another device, it's suppose to be additional.
...
Thanks
My first thought from reading that is that your boards are being starved of power as you connect more. Have you tried running each one singularly to make sure they perform okay. Then try them together on different power sources (if you have two or more PSU's available), so you've got PSU one to board one, and PSU two to board two etc, and let us know the results. What settings are you using in Hexminer, can you post a screenshot?
It's seems power issue but 2 of 500w psu connecting 4 boards only.
What is the make model of your power supply? It's probably got multiple low amp rails.
I use 350w/450w Enermax PSUs they spread the molex on 3 seperate wires and only cost <£30/$40 they run 3x/4x Hex16B no problem.
CIRCLE RAW POWER 500 WATT
Hard to find any info on this PSU I could only find this graphic in the Google cache as originals seem to be deleted from their web site.
If correct it may have only 28A x 12V = 336W on the 12v rail.
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But their web site says it's dual 12v rails so maybe it's 335W/2 = 168W max on a single rail/wire.That would explain why it's only powering 2x Hex16B.