Extending the power supply cables- how long can I go

[branskyj]

Hi all,
I am thinking of modifying my PC and more specifically- the power supply cables. What I want to do is keep the power supply at approximately 1 meter distance from the PC box. For that reason I need to extend most of the cables coming out of it so that they can reach the PC box and the motherboard.

Now, I see they sell 0.3 metres extension cables on-line. My question is though- what if I was to modify the extension cable myself and make it 1 meter by cutting and soldering additional wires. Would the motherboard still get the electricity it needs? Is there a limit as to what the extension cables should be?

It's not just about extending the 24 pin cable, it's also the cables for the graphics card, hard drives etc. I am doing the whole thing for aesthetic reasons- I'd like to keep the power supplies separately and out of sight.
Any thoughts?

Thanks guys.

 

[Rifter]

voltage drop could be an issue with the thin wires most PSU's use. I would upgrade them to 16ga and you should be ok. most are 18ga or 20ga stock.

 

[branskyj]

Thanks for the replay.
So, do you think 1 metre distance could lead to voltage drop?
Cheers.

 

[Rifter]

yes, the reason they use thin wire is because it is cheap and they are going very small distances with it. You are talking about making the distance over twice what it was designed to be which will more than double the voltage drop.

 

[branskyj]

Well, that's not good news :'(
I guess I need a new plan then.
Thanks for the help.

 

[Rifter]

16ga wire isnt expensive, i dont see the big deal in upgrading to 16ga. The price difference to 18ga is minimal.

 

[know of fence]

You are talking about making the distance over twice what it was designed to be which will more than double the voltage drop.

Voltage drop due to resistance of copper may also be a bit overrated, simply because it's the most basic electric law, familiar even to slackers like me: Resistance = Voltage / Amperage

There is also: specific resistivity(copper) = Resistance * wire thickness / wire length

You combine those equations and you get something like this: Voltage/wire lenght= resistivity(copper)*amperage/wire thickness.


Or you could just take the mΩ/ft resistance from this table( http://en.wikipedia.org/wiki/American_wire_gauge )for a certain wire (16 gauge) multiply with Amperage.

4.016(mΩ/ft) * 10A = 0.04016 V/ft (V lost with every added foot of wire.)

Even though this looks kind of high, thicker wire definitely could compensate for added length. What is the max Amperage on the 24pin motherboard connector?

 

[Rifter]

Voltage drop due to resistance of copper may also be a bit overrated, simply because it's the most basic electric law, familiar even to slackers like me: Resistance = Voltage / Amperage

There is also: specific resistivity(copper) = Resistance * wire thickness / wire length

You combine those equations and you get something like this: Voltage/wire lenght= resistivity(copper)*amperage/wire thickness.


Or you could just take the mΩ/ft resistance from this table( http://en.wikipedia.org/wiki/American_wire_gauge )for a certain wire (16 gauge) multiply with Amperage.

4.016(mΩ/ft) * 10A = 0.04016 V/ft (V lost with every added foot of wire.)

Even though this looks kind of high, thicker wire definitely could compensate for added length. What is the max Amperage on the 24pin motherboard connector?

I know all that, i just didnt want to get that technical. Either way going with 16ga would be a good idea.

 

[truckerCLOCK]

Also don't forget thicker wire isn't always better...you can have more resistance with thicker wire. 16 ga would be about right.

 

[Rifter]

Also don't forget thicker wire isn't always better...you can have more resistance with thicker wire. 16 ga would be about right.

This is not true, resistance always goes down with a thicker wire

http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

look at the ohms per 1000' column on that chart

 

[truckerCLOCK]

There are 4 things that effect voltage drop. Material, area (in circilar mills), length, and temperature. "Material" would be copper or aluminum. Aluminum has a higher specific resistance so there would be more voltage drop per foot than copper. "Area" would be the gauge of the wire. A larger gauge would carry more current and have less voltage drop. "Length" - resistance per foot of wire times the length. Longer wire means more resistance and more voltage drop. "Temperature"- Higher temps can cause more resistance causing voltage drop. I've read all the charts and guides, after 22 yrs of fixing people's house remodels and kitchen make overs I've seen everything... I'm not saying that your wrong I'm just saying use the "appropriated" size wire for each task.

 

[fffblackmage]

You're just being unclear. I think what you meant is that given two different thickness wires made of two different materials, it's possible to see the thicker wire having a higher resistance than the thinner wire. Rifter was probably assuming two wires made of the same material. I also made the same assumption.

 

[Rifter]

There are 4 things that effect voltage drop. Material, area (in circilar mills), length, and temperature. "Material" would be copper or aluminum. Aluminum has a higher specific resistance so there would be more voltage drop per foot than copper. "Area" would be the gauge of the wire. A larger gauge would carry more current and have less voltage drop. "Length" - resistance per foot of wire times the length. Longer wire means more resistance and more voltage drop. "Temperature"- Higher temps can cause more resistance causing voltage drop. I've read all the charts and guides, after 22 yrs of fixing people's house remodels and kitchen make overs I've seen everything... I'm not saying that your wrong I'm just saying use the "appropriated" size wire for each task.

Obviously, i was thinking this was a apples to apples statement, such as both wires being the same material.

Since if they are not the same material the statement is apples to oranges and that the reistance will change is kinda a givin.