I recently wrote a post all about the differences between all the PCIe risers currently on the market to power your GPU on a mining rig frame.

This included Molex, SATA & PCIe.

There's also risers with a combination of both.

I know when I first started out building my first mining rig I was a bit confused.

We're going to fight it out and put the Molex Vs SATA debate to rest.

I'll be upfront right now - Molex is the slightly safer option when it comes to powering a GPU riser SATA.

Should not be used.

SATA cables were never intended to power GPU risers.

There is a 3rd far safer option. Which I will mention below.

Why does the PSU matter?

A lot of the time they type of risers you're going to purchase is dictated by the type of PSU you may have. Most modern PSU's have an abundance of SATA connections.

Hard drives & optical drives back in the day all used to be powered by a Molex style connection.

This has changed since the introduction of the SATA connection. In fact, apart from maybe cooling fans, I can't think of any other modern components inside a PC that are now powered using a Molex connection.



The SATA Riser



SATA - which stands for Serial Advanced Technology Attachment was first introduced back in 2003. The first interfaces could carry up to about 150Mb/s.

Usually, it was hard disc drives that carried the SATA connection.

The average hard drive uses around 30 watts maximum power. Real world figures are closed to 20Watts.

This fact alone should tell you that SATA cables were never designed to be used to power mining GPU risers. If you are currently powering either the riser or GPU using a SATA connection your asking for trouble.

The worst thing that could happen is that there's an electrical fire as the SATA cable will melt eventually when under continuous load. What's more likely to happen is that your GPU will get fried due to differences in voltage as the SATA cable deteriorates.

If you've got something like a 1080TI that's a lot of money down the drain.



The Molex Riser



As mentioned the Molex riser is the slightly safer option. This is mainly down to the style of pin connection into the riser. You're not relying on a really small piece of copper. Molex cables have a pinout which gives them a better chance under continuous load.

Molex cables are designed to carry a maximum of 60 watts.

Watch out though as even if your using a Molex riser you can still be at risk due to the way in which connect the risers to the PSU.

Try not to daisy chain more than 2 or 3 risers off of one cable. This is asking for trouble.



The 3rd option



The safest option is the PCIe riser. PCIe cables are specifically designed to power such items as graphics cards. By design, you get a higher power output and can feel assured that your cabling is not going to melt.

However, there is a problem with PCIe type risers and that's how to power them all. Most desktop power supply units come with only 2 PCIe cables as standard.

If you've got a high-end PSU then you may have 4 PCIe cables out for use in with things like Crossfire/SLI.

This still is not enough to power a mining rig though. Minimum you're going to need 3 PCIe cables out from the PSU to power each graphics card (1 for the riser, 2 for the top of the GPU)

What's the solution?


Server PSU

I've written about the benefits of using a server PSU for GPU mining before. I'll briefly go into it again though.

Since the realization that you could use a server PSU to power GPU's the mining community has come up with the ingenious solution of a breakout board.

This is a printed circuit board (PCB) that attached to the most common HP server PSU style connection. On the other end of the breakout board are numerous PCIe outputs.

This is the perfect solution to power both a riser and the GPU.



A quick glance of my mining rigs and I see it has 12 PCIe connections. In theory, I'll be able to power 4 cards with this PSU alone.

Real world I do have my safety concerns so will probably limit to 3 GPU.s

Which riser then for PCIe?

Again I did go into detail on this in the solving the riser mystery. The best GPU riser on the market at the moment is version 006c. This is a GPU riser with a standard PCIe connection and voltage regulator.

1 problem

The only problem you face now is where to get male to male PCIe cables - they are a little hard to find but remember you'll need at least 3 for each GPU and you'll also need a good length or around 20cms.


Thanks for reading

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SCOTT MILLAR  //  IT Rockstar