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What type of cable for PC power cabling? - Page 2

post #11 of 34
Yes, all those Sata T-connectors are designed for AWG 18 wire. If you have an actual Molex Sata connector then you can see that from the specifications that some of the connectors also would allow the smaller gauges 20 or 22, but I guess that's because they have gold plating.
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post #12 of 34
Uhm just wanted to add that there are 18AWG cables with 2-2.2mm outer diameter. They should be preferred.
Example (German): click!
It's 18AWG with 2.03mm outer diameter, you should be able to find similar cables in your country.
post #13 of 34
Quote:
Originally Posted by Furion92 View Post

Uhm just wanted to add that there are 18AWG cables with 2-2.2mm outer diameter. They should be preferred.
Example (German): click!
It's 18AWG with 2.03mm outer diameter, you should be able to find similar cables in your country.

I already told this yesterday, see post #7 tongue.gif
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post #14 of 34
Quote:
Originally Posted by WiSK View Post

I already told this yesterday, see post #7 tongue.gif

you recommended a 0.75mm² cable which is NOT 18AWG wink.gif
Edited by Furion92 - 2/29/12 at 7:59am
post #15 of 34
Quote:
Originally Posted by Furion92 View Post

you recommended a 0.75mm² cable which is NOT 18AWG wink.gif

Technically you are correct, but you are literally splitting hairs: the difference is maybe 3 extra strands of copper.

The next biggest international size is more like AWG 17. What I linked is produced in Germany to an international standard size, what you linked is produced in the States and shipped over here for the sake of those 3 strands. That's reflected in the price too. The actual electrical difference is negligable since you are only using 2-4 amps out of the maximum 75 amps.
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post #16 of 34
I don't think I'm splitting hairs, WiSK. The 1mm² cable has got a 33% bigger section. My old P7 Dark Power Pro has got AWG16 cables, where you'd have to buy a 1.5mm² cables. The 0.75mm² cable is only half of that.
Also I would be interested where you've got the 75A value from?
Maximum Amps for chassis wiring (18AWG) is 16A and for power transmission 2.3A. That's nowhere near 75A.
post #17 of 34
Okay we make a nice discussion about it then smile.gif

But first I don't understand why you are suddenly talking about 1mm2. I believe AWG18 is 0.82mm2. The comparison I make was that AWG18 is only a few strands bigger than 0.75mm2. Here is a picture of the wire I linked, count the strands biggrin.gif

261

It's possible that some PSU manufacterers are using bigger wire, but they are also responsible for sourcing appropriate crimp pins and housings. But when suggesting to someone in a forum who wants to crimp and sleeve their own wires, it's not helpful to talk about bigger sizes. This will only make the job more difficult.

75A is the point at which 0,75mm2 twisted copper wire will melt. I'm just using that number as an arbitrary maximum to show that ATX specification is well within safety margin.
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post #18 of 34
Fair enough, AWG18 = 0.82mm² , that's right.
I just wouldn't feel comfy if my power supply had AWG16 cables on it and I'd replace it with 0.75mm². And the bigger the cable, the less resistance it has, which is obviously good for holding voltages steady.
The operating ranges for wires aren't limited only by their melting point, but also because of changing resistance while it's getting warmer. (-> lower efficiency, lower voltages...)
BTW: There are power supplies which can deliver even more than 75A over the 12V rail.

As far as I can tell, at least the crimps and housings on the component side are standardized by Molex, so the manufacturers have to make sure, that their cable works with the Molex crimps and housings.

Of course it's everyones choice, but for me it's a no-brainer that I'm going to avoid all possibilities and just go for the safe way (especially since it doesn't cost more and has got the same outer diameter).
post #19 of 34
Indeed, if your PSU has 16 gauge wires then it must be for a reason. That reason is because ATX specification arbitrarily recommends using this gauge for power supplies over 300W. However, they also specify that cables may be of unlimited length. I find it a bit contradictory. If we actually calculate the resistance of a longer wire (using a handy webpage), then you see that even for a cable of 1 meter long the voltage drop over a fully loaded (150W) PCIe 8-pin cable is only 0.09V with AWG18 and 0.06V with AWG16. So you can understand that I'm not so convinced about 16 gauge especially since most PSUs itself can vary its voltage by 0.3V or more. But now I am calculating for AWG16 and you are talking about the extra safety compared to my suggested wires. Unfortunately that page doesn't have a place to calculate 0.75mm2, but we can extrapolate to show that, with a wire length of 50cm there is less than 0.01V drop difference between the two. Neither will melt from powering a GTX590, in any case.

If you are worried about such resistances, then you better look at the connector pins. It's at least a factor more significant. Since these conduct by the pressure of 2 plates of metal, there is much more scope for accidental high resistance if the male and female pins do not mate correctly, or are of significantly differing alloys. You said that it's all standardised by Molex, but I don't know any of the PSU manufacturers who are using true Molex components. Buying 'quality' gold plated pins is also not the solution since the graphic cards all have tin pins and this will only increase resistance.
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post #20 of 34
Thread Starter 
Ok so the 6 pin heads came for the pci-e power or whatever they are called tongue.gif

I have 4 of the female heads and 4 of the male heads as im planning to make my own extensions of different lengths, however the female ones on the left of the pic came with the pins you can see at the bottom. From looking at the female socket on the motherboard it seems to have little pins without holes in them like the ones I have now. So to me it seems the female heads came with the female pins. What are the male pins that I need?

450

This, hopefully, is the last thing im going to struggle with but I thought before and I was wrong tongue.gif
The help is much appreciated.

P.S I ordered the wire you recommended WiSK so ill see what thats like when i get it. Im not powering anything super hungry on power anyway just some 560s smile.gif oh and some HDDs and SSD but i assume those are a fraction of the power compared to the gfx cards.
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