Power Supplies, Amperage, Watts, Will this Work?

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wsiono

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Hello,

I have been working on a system for some time, and i am now finding that i am largely ignorant in the finer aspects of Power Supply Units.

The unit in question is a Corsair HX750, which SEEMS to be single-rail, at about 62amps.

Two questions :

1. Is it safe to run 3 Hard Drives, 1 DVD Drive, and 11 Case Fans on a single PSU cable?
2. Is it safe to run the above, in addition to the PSU supplying power to an FX-8350, Motherboard, Radeon HD7870 Crossfire, and Xonar Essence STX Sound card?

I've been told the watts are fine for the above (750w on the PSU in question), but i would like to hear from others, and also i would like to hear about the/any potential amperage issues along that cable, and regarding the whole system.

Will the Corsair HX750 power all the components, and can it run all the mentioned components on a single SATA power cable?
 
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Why not just use the cables that came with your power supply as intended? It's already modular so clutter will not be an issue although even a non modular unit can have the cables hidden to look great. There is a reason for all those cable routing holes in your case.

Your amp chart is way off.
11 fans at 5 watts each = ~5a
7870s pull about 130w each so lets say 275 watts for 2 just to be safe. So 23 amps. You have 37.5 amps confused with the power needed for an entire system not just the cards.
FX 8350 is a 125w chip. Maybe 140w overclocked. So 12 amps to be safe.
Hard drives use about 7 watts each so lets say 25w for 3 at max load or 2 amps.
Everything else, OK lets say 60 watts or 5 amps to be safe. Most of this is not running off...
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Deleted member 217926

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You are more than fine. 7870 Crossfire only needs a recommended 600w PSU.

http://www.realhardtechx.com/index_archivos/Page362.htm

So not only is what you have a very high quality unit it is also way more than you need. Hard drives use about 7 watts at full load. Case fans use about 5 watts on high. You have nothing to worry about. If it was possible to run a 3 way Crossfire of 7870s you would still be good.
 
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A molex connector can supply 11 amps for 132 watts. 3 hard drives at full load = 21 watts. 11 case fans on high = 55 watts. DVD drive adds less than 10 watts on full load.
55+21+10 = 86 watts.

Totally safe even with all at 100% load.
 
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wsiono

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Just to clarify, i am hoping to run a single SATA(x4 connector string) cable from the PSU. The first two connectors to power a HDD carge (with 3 hard drives), the third connector to power the DVD drive, and the fourth connector will be split from one SATA connector (female)(with one of these : http://www.amazon.com/dp/B002LBROAA/ ) to 2x Molex male, which will then be connected to two of these ( http://www.frozencpu.com/products/14094/ele-936/Phobya_4-Pin_Power_Distribution_PCB_6x_3-Pin_Block_81097.html ), which will have the fans connected to the 3 pin connectors.

This is all on a single cable with four SATA female power connectors. You're suggesting this is safe?
 
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Goodeggray

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Electrically you can do it. All the current will come from the single 12 volt rail but given you parts choices why do you feel you'll need 11 case fans to cool it. None of them run super hot. Noise is going to be a problem. Get a case with better cooling. Plus with so much plugged into one cable wire management is going to be bad, and the HX750 has plenty of connections.
 
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Deleted member 217926

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Wait you are going to use a SATA cable for fans? That's.......different. I'm less certain that would work. I would use a SATA cable for the hard drives and DVD drive and a standard Molex cable for the fans. I think a single SATA cable would theoretically work but it only supplies 4.5 amps ( 54 watts ) from the 12v rail and that is what the fans need. So I would not try it.
 
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wsiono

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It's a Lian-Li D600, it's double wide. 3x front intakes, 1 rear, 2 top exhaust, and 3 rear intakes our exhausts (i want to do positive pressure, so i am trying to use those as intake), and then, 2 fan modules for 6 of the front bays. It's really not necessary, but i don't like having those space un-filled. I am running corsair AF quiet editions, (25.5db), so hopefully it won't be too loud, and in either case, it's probably a lot quieter than what i'm using right now (maybe...)

I am also trying to use a single cable just because it would work out nicely for cable management and use if it did, then i wouldn't have two un-used molex connectors being un-used. Would be great if the PSU came with more connecter per cable options...

 
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wsiono

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What if i used a single Molex cable with four connectors from the PSU and converted molex to SATA power for the HDDs and DVD, and then used the remaining available connector with a splitter? Would that be preferable?

 
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Deleted member 217926

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^ Yes that would be better as per my first post but why don't you just run 2 cables? It's a modular power supply. Not like 2 cables will be cluttered. Hiding cables should be easy in a Lian Li case. They are generally top notch.
 
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wsiono

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I suppose i could run two cables and just rout one of them all over the place before connecting it.
I only recently realized that the HDD cage i'm going to be using ( http://www.newegg.com/Product/Product.aspx?Item=N82E16817994153&Tpk=MB973SP-2B ) uses Molex, and the fans use Molex. The DVD drive is the odd-man out. So i may just purchase a Molex to SATA and use that on the DVD drive (which is really only for very occasional use.)

I really appreciate all of the help, all :)...
 
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wsiono

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I made a rough layout of what i'm going for :
gP7a8aZ.jpg

Just an update, really, for clarity.
Again, i really appreciate the assistance. I've been researching PSUs, amps, etc. nearly all weekend...
 
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wsiono

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Another question,

I've worked out the amps per component as such :

3 amps = 11 fans
37.5 amps = 7870 crossfire (OC edition)
20 amps = fx-8350
2.08 amps = Xonar Essence STX
3 amps = HDD (x3)
Motherboard = 5-ish?

I found the above values by assuming 12v for volts, and trying to find the watts for individual pieces. (for instance, called XFX to ask about the 7870 OC edition, they said about 450 watts for both cards, max).

Is this sound?

When added, they exceed the 62 amps of the 12v rail available on the HX750. These ARE rounded up, but is the HX750 still capable? Or should i be looking for something with a higher amperage on the 12v? I would like to avoid cable melting electrical fire :(...
 
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Deleted member 217926

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Why not just use the cables that came with your power supply as intended? It's already modular so clutter will not be an issue although even a non modular unit can have the cables hidden to look great. There is a reason for all those cable routing holes in your case.

Your amp chart is way off.
11 fans at 5 watts each = ~5a
7870s pull about 130w each so lets say 275 watts for 2 just to be safe. So 23 amps. You have 37.5 amps confused with the power needed for an entire system not just the cards.
FX 8350 is a 125w chip. Maybe 140w overclocked. So 12 amps to be safe.
Hard drives use about 7 watts each so lets say 25w for 3 at max load or 2 amps.
Everything else, OK lets say 60 watts or 5 amps to be safe. Most of this is not running off the 12v rail anyway so would not apply but sure lets be overly safe.

5+23+12+2+5 = 47a. And that is largely overestimating.

Your power supply is fine. Not sure how many more times I can assure you. Most people have no idea just how little power a modern computer uses. I see people with systems comparable to your with 1000w units all the time and it just makes me laugh. As the link in my first post shows all you need is a quality 600w unit for your setup.
 
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