Quote from: Doff on December 22, 2013, 11:24:59 PM

Quote from: Keefe on December 22, 2013, 10:15:52 PM

There's another reason to use more than 2 cables: reducing the power bill.

Let's assume the wires from the PSU to the rig are 18 gauge and 2 ft long, and the rig uses 600W. With two cables (don't use a single cable with two plugs!), we have 6 wires for each of + and -, each carrying 8.3A of current. Each of those 12 wires has a resistance of 0.0128 ohms*, so the voltage drop at 8.3A is 0.106V and the wasted power is 0.88W per wire, for a total waste of 10.6W. If you figure on running these rigs for 6 months and your power cost is $0.15/kwh (mine's twice that), you waste $6.95 just to heat the wires. The connectors probably add significant resistance and therefore waste even more power.

Now let's run the numbers for 4 cables instead of 2. 24 wires, 0.0128 ohms, 4.15A, 0.053V, 0.22W/wire, 5.3W total wasted on heating the wires. As a general rule, doubling the number of wires (or their cross-section area, i.e. 15 gauge vs 18 gauge) sharing the same load halves the power wasted. You save at least $3.47 over 6 months and reduce the risk of fire due to overloaded connectors.

Since my power costs twice as much as the examples above, I went a little overkill and made cables with one 12 gauge wire instead of three 18 gauge wires, for my modular PSUs, with male PCIe plugs on one end to fit the PSU and ring terminals on the other, for a total of eight 12 gauge wires (four +, four -) per rig.

* http://en.wikipedia.org/wiki/American_wire_gauge

So you just made me realize I need to buy two of those Extenders. Is it ok to connect two ring connectors to each terminal like that? At least that's the only way I see connecting for pci connections.

I have 4 ring terminals on each screw. I'm using 4 of these for a rig: