Noob mobo molex mining rig question

Hi, I have the ASRock H81 Pro BTC Super Alloy and an EVGE 750 G2. I have a question that may seem obvious but I cannot find info anywhere thus far.

On the mobo there are 2 PCIE power Molex slots. I understand that you need to power these slots from the PSU when using more than 2 GPUs. (we want to hook up a 3rd GPU - I presume we’d need a 2nd PSU if we were going to power more than 3)

However, the only lead which came with the PSU that has a molex connector is the cable labelled PERIF. I thought the PERIF would be used for powering things such as my external fans on my frame. Should the lead be plugged in here or do I need an adapter to plug it into one of the SATA connections?

(I notice the PERIF and SATA connectors for the PSU end have different connectors inside the end of the lead so assume they perform different functions). Hopefully this makes sense to somebody, if not can somebody link me to somewhere where I can find the answer.

Thanks in advance!

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Hey buddy!

Can you attach a picture of your motherboard and point out where those two power sockets are?

Even though I know the mobo, I never dealt with it directly.
I’ve assembled many computers and never had to plug anything from psu to mobo because of a multiple GPU conection.

The only two slots laid on the mobo that look like pci-e ones are the CPU power slots. But you can easily find those by the processor.
The only cables that come out of the psu and get plugged directly to the motherboard are the
main board power feed (also called 24 pin cable) and the cpu power feed,
other than that I don’t know.

You’re right about that, I’ve got the same PSU brand (also a G2). However, assuming that molex has to be plugged as you say then the perif cable will do just fine.
Try going to ASrock’s site and downloading the manual, if it’s not there try emailing customer support guys.

If I’m correct, you can plug a sata cable on the perif slot (PSU end) and it will work just fine. At least that’s what I did yesterday in order to plug a riser and the riser turned on perfectly well.

Oh, one more thing, I think for just 3 gpu’s you won’t need to give the mobo extra power but once again I have a different mobo so it’s just my assumption.

I hope I could help!


Perif and SATA provide similar power and can be adapted to one another. So your GPU’s are going to determine if you need another power supply. For 3 cards you should be fine. Here is a picture to help.


awesome thanks so much :slight_smile:


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