I have an enlight 300W PSU. It has 4 molex..now I have a HD, dvd-rom, 1 crystal orb, 1 80 delta fan and 6 120mm fans. So I have 10 devices sharing 4 molex. Is this okay? Does every single molex on a system gets the same amount of power? let say my 80mm delta fan connect to 1 of the 4 PSU main molex, then my HD connect to the 80mm molex and then my crystal orb connect to my HD molex. Do they get the same amount of power? Or the last device will get the least amount of power(a molex shares by 6 120mm fan, that mean the last fan)?? Thanks.
Does every single molex on a system gets the same amount of power??
- Thread starter CyNics
- Start date
Is it really this necessary to have 6 x 120mm fans in a case? It sounds like a bit much to me.
I would be tempted to say that yes each gets the same amount of power but I don't think this is true.
I have been told before to keep things like hard drives as separate from other devices as possible when connecting power cause they have to have a reliable flow of current and one other device may drain or use more power causing fluxuations to the hard drive.
I would probably try to limit the number of fans for one thing and then use the hd on one, dvdrom on another and then share the last two between all the fans that you use (ie. maybe limit to 6 fans: 3 on each remaining molex). Either that or try to put some fans off of the mobo headers, except the 80mm delta, make sure that's directly off the psu. That's a couple of options, but you could always just get a new psu like an Antec, Sparkle or Enermax with more juice and more connectors.
I'm sure there's a faq floating around here somewhere which states the power load off of each molex and general practices.
I would be tempted to say that yes each gets the same amount of power but I don't think this is true.
I have been told before to keep things like hard drives as separate from other devices as possible when connecting power cause they have to have a reliable flow of current and one other device may drain or use more power causing fluxuations to the hard drive.
I would probably try to limit the number of fans for one thing and then use the hd on one, dvdrom on another and then share the last two between all the fans that you use (ie. maybe limit to 6 fans: 3 on each remaining molex). Either that or try to put some fans off of the mobo headers, except the 80mm delta, make sure that's directly off the psu. That's a couple of options, but you could always just get a new psu like an Antec, Sparkle or Enermax with more juice and more connectors.
I'm sure there's a faq floating around here somewhere which states the power load off of each molex and general practices.
your computer must sound like a freakin NASA rocket! 6 120m and 1 delta!
well for my system, i have my 2 hd's on 1 connector, 1dvd,1cd-rw on another, and my 2 fans on another(i need a better intake fan)
but i dont know about your original question, it might depend on the power supply or might not, but try to keep the fans to themselves atleast
well for my system, i have my 2 hd's on 1 connector, 1dvd,1cd-rw on another, and my 2 fans on another(i need a better intake fan)
but i dont know about your original question, it might depend on the power supply or might not, but try to keep the fans to themselves atleast
hey..they aren't delta screamer 
they are actaully very very very quiet 1500-2000rpm
back to the question..so what you mean is all of them are getting the load requirements they need rite? and not the last device that is connected to a parrallel setting gets the least amount of power?
they are actaully very very very quiet 1500-2000rpmback to the question..so what you mean is all of them are getting the load requirements they need rite? and not the last device that is connected to a parrallel setting gets the least amount of power?
well every plug on the same set of wires gets the same amount of power, but i'm not sure if each set of wires that comes out of the PSU is on a different (insert electrical device terminology here) or not. if they're all sharing the same source of 12v/5v power than it doesnt matter, however i dont know if thats how it works. cmon, EE dudes, chime in
here's the deal,
first of all, unless you have a monster of a case, you are way past overkill with the 6x120mm case fans. There's no way with that many fans you can have optimal air flow. A bunch of fans in a case blowing air in and out can do very little unless setup correctly. i wont babble about efficient case cooling, you can find plenty of that online, but as far as your power question goes... yes, every single molex on a system gets the same amount of power. here's a brief explaination:
Power (in watts) is the product of Voltage (in Volts) and Current (in Amps). In other words, P=VI, where I = current. Since the voltage used for these devices is uniform, what you really mean to ask is "Do they give off the same amount of current." On your power supply you should see a chart that details these specs. Each molex connector has 3 wires running into it: a -12v wire, a -5v wire, a 5v wire, and a 12v wire. Your power supply is rated to supply a maximum current on each of these channels, regardless of which set of wires you are using. If you have a maximum of 60A for your 5v source (i can't remember what modern PSUs usually provide), that means that the sum of the current being used by all the devices in your machine on the 5v channel cannot exceed 60A. If you try to use 70A of current, and your power supply can only provide you with 60A of current, you'll start running into system instability or an all out lack of functionality.
I dont think i did a great job answering your question there, so let me explain this in clearer terms should that not make sense: Say you have a power supply that can provide 80A on your 5v channel. Coming out of your power supply you have 4 molex connectors. What this means is that the current being drawn from the 5v channel for all the devices added together cannot exceed 80A. This does not mean that each molex connector can supply 20A, making a total of 80A. One channel could supply 50A, and the others 10A each. It all depends on how you use it. All you have to do is make sure that the total current being used throughout your whole machine for that channel does not exceed the rating. It doesn't matter what channel you plug them into.
Now, with that said, I'll explain why it actually does matter what channel you plug them into. You want to provide a certain voltage to each device. Like I said above, there are 4 voltages available: -12v, -5v, 5v, 12v. If you have 24 devices all connected to the same molex connector in a string, as in the following crappy diagram, you could run into a problem with resistance.
PSU ---Molex # 1-------- HDD ------------- HDD --------- HDD -------- HDD ---------- CDROM -------- Too many fans -------- etc...
In other words, the resistance of the 24 devices, each of which is minimal and insignificant alone, could add up to be so great that by the time you get to device #24 in the chain, you have 4.5v instead of 5v. Modern power supplies are switching power supplies - meaning that they automatically adjust for this, but if the current is already overloaded you will have a problem providing the correct voltage.
I'm pretty sure all that is accurate, but i'm just a freshman ECE major so i'm not 100% sure. I could be a little off on the resistance part, but I know that as long as you stay reasonable w/ the # of devices on 1 molex, and stay within the maximum current per channel as specified by the PSU label or spec sheet, you should be OK.
Hope I helped,
Joe
Theoretically, you can hook up an infinite number of devices on an infinite number of molex connectors provided your power supply can give off an infinite amount of power and your devices all have 0 resistance.
first of all, unless you have a monster of a case, you are way past overkill with the 6x120mm case fans. There's no way with that many fans you can have optimal air flow. A bunch of fans in a case blowing air in and out can do very little unless setup correctly. i wont babble about efficient case cooling, you can find plenty of that online, but as far as your power question goes... yes, every single molex on a system gets the same amount of power. here's a brief explaination:
Power (in watts) is the product of Voltage (in Volts) and Current (in Amps). In other words, P=VI, where I = current. Since the voltage used for these devices is uniform, what you really mean to ask is "Do they give off the same amount of current." On your power supply you should see a chart that details these specs. Each molex connector has 3 wires running into it: a -12v wire, a -5v wire, a 5v wire, and a 12v wire. Your power supply is rated to supply a maximum current on each of these channels, regardless of which set of wires you are using. If you have a maximum of 60A for your 5v source (i can't remember what modern PSUs usually provide), that means that the sum of the current being used by all the devices in your machine on the 5v channel cannot exceed 60A. If you try to use 70A of current, and your power supply can only provide you with 60A of current, you'll start running into system instability or an all out lack of functionality.
I dont think i did a great job answering your question there, so let me explain this in clearer terms should that not make sense: Say you have a power supply that can provide 80A on your 5v channel. Coming out of your power supply you have 4 molex connectors. What this means is that the current being drawn from the 5v channel for all the devices added together cannot exceed 80A. This does not mean that each molex connector can supply 20A, making a total of 80A. One channel could supply 50A, and the others 10A each. It all depends on how you use it. All you have to do is make sure that the total current being used throughout your whole machine for that channel does not exceed the rating. It doesn't matter what channel you plug them into.
Now, with that said, I'll explain why it actually does matter what channel you plug them into. You want to provide a certain voltage to each device. Like I said above, there are 4 voltages available: -12v, -5v, 5v, 12v. If you have 24 devices all connected to the same molex connector in a string, as in the following crappy diagram, you could run into a problem with resistance.
PSU ---Molex # 1-------- HDD ------------- HDD --------- HDD -------- HDD ---------- CDROM -------- Too many fans -------- etc...
In other words, the resistance of the 24 devices, each of which is minimal and insignificant alone, could add up to be so great that by the time you get to device #24 in the chain, you have 4.5v instead of 5v. Modern power supplies are switching power supplies - meaning that they automatically adjust for this, but if the current is already overloaded you will have a problem providing the correct voltage.
I'm pretty sure all that is accurate, but i'm just a freshman ECE major so i'm not 100% sure. I could be a little off on the resistance part, but I know that as long as you stay reasonable w/ the # of devices on 1 molex, and stay within the maximum current per channel as specified by the PSU label or spec sheet, you should be OK.
Hope I helped,
Joe
Theoretically, you can hook up an infinite number of devices on an infinite number of molex connectors provided your power supply can give off an infinite amount of power and your devices all have 0 resistance.
Sorry ZTadmin, but you need to revise your 'Resistors in series and parallel' equations.
You won't get a voltage drop by connecting too many devices In Parallel which is how Molex connectors work. The resistance drops as you add more devices because ( 1/Rt = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn) Where Rt is the total resistance and R1 R2 etc are the individual loads. As the resistance drops, the current increases ( since I = V/R ) where V is constant (ie. as R decreases, I must increases) Voltage drops are therefore not a problem unless you're drawing more current than the PSU can handle, in which case component failure will cause a voltage drop.
The important thing is that the current on either the 5v or 12v lines does not exceed the rated amount (normally written on the PSU itself.) To answer your question, all components run of the same segment inside the PSU regardless of which molex you attach them to. There are only multiple molexes for the sake of convenience.
PS. The wires on the molex are +5v 0v 0v +12v (yellow +12v, red +5v) - The Psu puts out no negative voltages (except -3.3v on the ATX connector, I believe.
Hope that helps, if it needs any clarification just ask.
(edit to replace a mistyped which resulted in most of this being in bold)
You won't get a voltage drop by connecting too many devices In Parallel which is how Molex connectors work. The resistance drops as you add more devices because ( 1/Rt = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn) Where Rt is the total resistance and R1 R2 etc are the individual loads. As the resistance drops, the current increases ( since I = V/R ) where V is constant (ie. as R decreases, I must increases) Voltage drops are therefore not a problem unless you're drawing more current than the PSU can handle, in which case component failure will cause a voltage drop.
The important thing is that the current on either the 5v or 12v lines does not exceed the rated amount (normally written on the PSU itself.) To answer your question, all components run of the same segment inside the PSU regardless of which molex you attach them to. There are only multiple molexes for the sake of convenience.
PS. The wires on the molex are +5v 0v 0v +12v (yellow +12v, red +5v) - The Psu puts out no negative voltages (except -3.3v on the ATX connector, I believe.
Hope that helps, if it needs any clarification just ask.
(edit to replace a mistyped which resulted in most of this being in bold
) You mean the 5v, 12v channels or the 4 molex connectors?
Your explanation is great
Thanks.*my 120mm fan isn't a monster fan. Please. They spin very slow(very very slow and quiet) and they aren't delta screamer
*ztadmin: i do have a monster case
There will be a sticker on the PSU detailing how much current the PSU can supply on each rail (something like 30A on 5v and 15A on 12v) so the total current draw of everything connected to a 12v supply, regardless of which molex is plugged into, must not exceed that figure. Same for the 5v supply.
You know, WoodChuck2000, the scary thing is that I learned enough electronics to know what you just said above.
RL's in Parallel, voltage doesn't change, so current must increase.
Ohm's law prevails again.
I both loved and hated electronics....
RL's in Parallel, voltage doesn't change, so current must increase.
Ohm's law prevails again.
I both loved and hated electronics....
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