Bitcoin Forum

These boards seem to have 2x molex power supplementation specifically for the PCI-E slots

I am wondering if I need to power the risers even on these boards since the mobo is technically supplying the extra power needed?

With Pro BTC boards I don't use the 2 extra molex on the mobo but I only use powered risers. It wouldn't hurt it though but it's not necessary at all.

If you use unpowered risers (you can't just not power powered risers, they don't work without power) then you should definitely use the two molex on the board.

But even then you'll probably burn some wires or your mobo if you use 5-6 power hungry cards (that prefer pulling from PCIE instead of 6/8-pin) because each powered riser supplies 60-75 watts and the 24 pin and the two molex on the board will going to be overwhelmed.

i use both the molex on board and powered risers and never have had a problem so I never stopped doing that.  =)

That's fair and definitely understandable, I will stick with the nice newer powered risers then, fully connected.


Buying the rest of the parts for my first rig this week and just trying to hammer out the details concerning power. I think I want to do a dual PSU rig; HP server PSU for the risers and GPUs, then a smaller ~500w ATX PSU for the mobo/cpu/ssd/etc.

those server PSU are loud as hell.  Personally i do a EVGA 1300 and 6 RX cards and i run at no more than 1k watts

Damn.. well I am glad I am still researching then. I appreciate your input man. I am an experienced PC nerd with several enthusiast builds under my belt, so I was hoping a lot of that experience would translate. Zero experience with servers though, so good to know for sure.


One of my concerns with the ATX PSU's is the lack of enough full 8pin PCI-E outs. I see several mining sites selling these 6pin to 8pin power cable adapters. Wondering if those are safe to use as long as the PSU has the capacity?

6 GPUs aren't exactly silent either.

yeah but that high pitch wine of the server power supplies make me want to punch a baby. 

6 cards are not horrible but yeah not quiet.  EVGA 1300 come with 6 pci outs and 6 cables so You can go 1 to 1.  Don't use any more splitters than you have too. 

Powered risers don't take any power from the mobo so those molex connections are useless. Better to use them
to balance the power distribution to the risers.

I have 48 machines running 6 cards each on an asrock H97 anniversary with non powered risers. I just plug the single extra molex in on the board and everything works fine.

also need to consider the cards themselves, some have a vrm design where all the power in comes from the pcie power

Excactly, either the extra mobo power connections or powered risers, don't need both.