Things have now regressed. I think my Mobo and CPU are struggling to boot all 3 cards. I have an older Z87 chipset and i7 875k CPU. It will not consistently recognize the cards. PCIe speeds are suspect at this point. I have to manually set Gen3 speed. It will not accept auto detect, nor and speeds below Gen3
i assure you a properly set up and bog stock, comparatively weak by todays standards cpu like an q6600, has NO problem with a r9 390 and r9 380 with a hd6870 mining crypto. and it gets 21 mhs and 31 mhs at eth, which is exactly right with others gpus. oh and plus sia and decred as dualies
you setup is wrong somehow.
My "big rig" ran a Semperon 145 (SINGLE CORE semi-current CPU) to support 3x R9 390s for quite a while.
No issues.
Only reason I swapped a X240 dual-core into it was that the MB the X240 was on died, and I figured long-term I might need more CPU if/when Ethereum gets unprofitable and I need to do other stuff on that machine.
The MOST dual-width cards that will physically fit on any ATX board is 4 - there are a few different motherboards with applicable spacing, though the Biostar "Racer" one linked above is the lowest-cost new board that can manage that.
ATX spec calls for a maximum of 7 slots TOTAL, which is the core limit.
I specifically remember an ECS varient with the same theme, 1 or 2 others with the same theme but I forget what brands, and there was the one Gigabyte with *7* PCI-E 16 slots (they obviously didn't all RUN at 16x at the same time of course).
Server boards and PCI-E "expansion" boards that can handle more than 4 dual-slot cards plugged into them are ALL very expen$$$ive - you can build a complete SYSTEM with 4 RX480 for just the cost of some of those server motherboards ALONE. NOT WORTH IT.
the biostar is on sale for---------------------------------------------------------------------------------------- 110
my setup is with an i3 6100 not a i3 6100t ( I have 9 pc's most idle I can lose track)--------------------- 129
I used the m2 card ssd 250gb 66 bucks overkill but 20 more then the 128 gb ssd---------------------- 66
2 sticks of 8gb ram was 64 bucks ----------------------------------------------------------------------------- 64
corsair ax 760 ------------------------------------------------------------------------------------------------- 132
windows 7 pro ------------------------------------------------------------------------------------------------- ?
bench case from newegg
http://www.newegg.com/Product/Product.aspx?Item=N82E16811353001 --- 40
all of the gear above I already had from mining with the nanos. it comes to 540 if you have none of the above.
the biggest problem is getting the rx 480's
I could make 4 of these 16 cards 400 maybe 410mh and about 2300 to 2400 watts. not going to happen as I have a lot of other gear and I won't buy 2 more bio-star mo-bos
anyway, thanks for sharing your rig and your numbers.
