Powered or unpowered risers?

I know that there were many topics on this subject, but they were all in conflict with each other, so I decided to write a new one.
I've seen a lot of topics, where the motherboard was melted when used powered riser and lots where melted using unpowered.

So my scenario is - I plan to build a 6-gpu miner, what will be not underclock, but overclocked (free power).
It will have 3 PSU:
- 1 modular PSU 1200W - one 12V 95A line - for motherboard H81 pro btc, some cheap g3260 cpu and connect 2 RX 480 8GB cards external pins
- 2x cheap PSU 800W - each have 2 gpu line 12V 30A - each for RX 480 8GB cards external pins
I estimate with overclock each card will take 250-320W (depends on what algo use)

My question, should i use powered or unpowered risers, 6x75W for pci-e is 450W, can H81 pro btc support that? Topic say "do not use" powered risers with h81 pro btc, but there been topics where motherboard melted because of big power draw.

Always always always always use Powered risers, especially on any RX series GPUs.

Thank you for the suggestion. I know that all powered risers have to be connected to PSU with motherboard, but should I do anything else to keep safe motherboard?

Quote from: chronek on November 21, 2016, 12:02:09 AM

Thank you for the suggestion. I know that all powered risers have to be connected to PSU with motherboard, but should I do anything else to keep safe motherboard?

They can be connected to either PSU, just make sure both PSUs are grounded together.

How grounded? Can I connect any ground wires from PSU, or they should be specific from used power line?

Any wire as long as its ground.

So if one GPU is plugged in with 1 PSU by the PCIe connectors, and that same GPU has a riser connected with a GND to another PSU, they are grounded together. Since the GND on the GPU is connected on both ends.

Quote from: adaseb on November 21, 2016, 12:14:29 AM

Any wire as long as its ground.

Thanks, You helped me get rid of doubts.

why dont you just powered the entire system with your 1200 PSU?? I powered my 6 cards with only 1000w and that is with risers on a gold rated PSU.

Quote from: mewhoyou on November 21, 2016, 12:23:01 AM

why dont you just powered the entire system with your 1200 PSU?? I powered my 6 cards with only 1000w and that is with risers on a gold rated PSU.

First it will be overclocked, i estimate it will take about 2000W, second i want keep safe, so all PSU will be max 75% in use, third maybe ill split pci-e and add some more cards

There really is no point in overclocking your RX 480s. They might only run 10% faster in ZEC but use like 30% more energy.

In ETH overclocking your engine core does nothing.

Just because it uses double the power doesn't mean it will hash twice as fast.

I have power for free, so 30% more energy will cost me nothing, and i do not know if i will mine zec or eth in future

well you are so carefull of not to damage your motherboard and psu but you should also avoid oc as well... first card will make a shitton noise more , second the fan will most likely break down , third , prolly voltage regulators or capacitors or memory or all three are gonna melt faster especially with wrong model card that does not dissipate heat in correct way.... is it worth it ? for a mere 20 % more ? we are not speaking of thousands but of few hundreds dollars per year.... man just leave oc ...

Yes of course there is zero reason to ever use non-powered risers with modern gpus. Especially a RX 480 depending on your driver. Spend the extra $5/card and power the riser.

What on earth makes you think you're going to be pulling 320w from each card?? You'll be fine with just the 1200w.

i do not care about noise, cause will work in garage, i always oc cards but without increase voltage, still they take more power as well, i said will try other algo and coins, and there are some power hungry