PSU - Power Supply - Single Rail


NAS

Recommended Posts

BTW, the Corsair 750 is on sale right now at Newegg for ~$100 after rebate.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139006

 

Free shipping, too.

 

 

Cheers,

Bill

 

$82 shipped with the promo code right now. When that's expired, Provantage has been cheaper than Newegg on these all summer (I keep looking up prices on the 1000HX).

 

http://www.provantage.com/corsair-memory-cmpsu-750tx~7CSMC05E.htm

 

EDIT: $74 after rebate from buy.com.

5% off coupon. http://www.buy.com/retail/coupon.asp?prid=84773074

http://www.buy.com/prod/corsair-750w-tx-series-80-plus-certified-power-supply-corsair-tx-cmpsu/q/loc/101/206178325.html

 

Good call.  I was looking at the final price on screen and forgot about the MIR.  BTW, for whatever reason I didn't finalize the deal on the 650 over the weekend like I thought I had, so I went ahead and bought this one.

 

 

Bill

Link to comment

Does it matter how many sata plugs there are on a single power supply?  Are there adapters/splitters that one can use to power numerous drives? 

 

Yes it does. Please see wiki page.

 

The PC Power & Cooling 750 Silencer Quad is one of the most popular single rail for enthusiasts.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817703009

 

Couple of points: its not modular (but none seem to be so far), i cant find proper specifications for the noise/efficiency etc that lists test results etc like the Corsair does.

 

This is the official unRAID PSU isnt it?

Link to comment

Does it matter how many sata plugs there are on a single power supply?  Are there adapters/splitters that one can use to power numerous drives? 

 

 

Yes it does. Please see wiki page.

 

 

This page?  http://lime-technology.com/wiki/index.php?title=PSU

 

I don't see anything addressing this specific question, unless you mean that a single rail supply will deliver full power on any of the leads.

 

The PC Power & Cooling 750 Silencer Quad is one of the most popular single rail for enthusiasts.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817703009

 

 

Couple of points: its not modular (but none seem to be so far), i cant find proper specifications for the noise/efficiency etc that lists test results etc like the Corsair does.

 

This is the official unRAID PSU isnt it?

 

You mean the one that Tom ships with his pre built systems?  That would be the PC Power & Cooling Silencer 610 EPS12V

Link to comment
Does it matter how many sata plugs there are on a single power supply?

 

Would you mind rephrasing the question?  I'm not sure what you are asking.

 

Are there adapters/splitters that one can use to power numerous drives?

 

Splitters like this are commonly used.  Do make an effort to balance the number of drives (of any type) on each of the drive cables provided from the PSU.

 

Edit: removed 'small'

Link to comment

Are there adapters/splitters that one can use to power numerous drives?

 

Splitters like this are commonly used.  Do make a small effort to balance the number of drives (of any type) on each of the drive cables provided from the PSU.

 

One should keep in mind, Splitters are common and easy, however, the wires and molex connectors are rated for a certain amount of current and when that is exceeded you have a potential problem.

 

So.... even though your kickass power supply may supply oodles of amps on a single 12V rail, the wires and molex connectors are not rated for the same load.

 

Therefore balancing of load is important of you are exceeding the amount of physical connectors.

I have seen power supplies melt the wires right in front of my eyes too.

I think the issue that disturbed me the most was the power supply did not shutdown. The wires were red hot and melted the plastic revealing glowing copper, but the power supply stayed on.

 

Keep in mind, There's a reason current is limited via multiple rails.

 

Balance and care is important.

Link to comment

NAS, have you had a chance to read all the way through the JonnyGURU thread yet?  (Thanks, Koperfild, for that link.)  It puts a more complete perspective on the single/multi rail question.  It appears to me that if you balance your drives across all of the power cables provided, the whole question becomes a moot point.  For safety, you still need to restrict any power cable to a maximum of 20 Amps, and that becomes the more important rule for guidance.  The single rail could even be dangerous, for someone who does not understand it.  They might think that they can attach 14 more SATA power connectors on one of their SATA power cables, and hook up 16 drives on that one cable, because after all, they think they can handle 60 Amps on it!

 

Perhaps a better 'rule of thumb' is, whatever the type of power supply, divide up your drives across all of the provided drive power cables.  Never have more than 8 drives on any one cable (not sure if 8 is the best number).

Link to comment

Good points RobJ, and this is a great discussion to help everyone understand.

 

What I question is how do you balance drives among rails without knowing the total architecture of the power supply.

 

From what I read, the rails are usually divided up among,  Peripherals (molex/sata), motherboard & CPU connectors, PCIe connectors.

My perspective leads me to believe you can't really balance peripherals between rails, yet the advice of balancing per wire is very important, I would even say crucial considering the size of disk arrays we are  talking about supporting.

Again, I've read that the wire and molex connectors can take a certain amount of amperage before heating up.

 

Have I exceeded peripherals per molex wire in the past.. Yes, but it;s a small amount compared to the drive systems we are seeing today.

 

There is a part of me that believes the multiple drive bays offered in todays market,  help alleviate the issue of current draw and physical connections.

I.E. I've seen 5in3's with 2 power connections, making me believe this suffices for physical foundation for the power draw.

 

Comments?

 

Link to comment

Perhaps a better 'rule of thumb' is, whatever the type of power supply, divide up your drives across all of the provided drive power cables.  Never have more than 8 drives on any one cable (not sure if 8 is the best number).

 

Yep. Balance the load on the power cables. The way I deal with connectors is I try not to use more than what comes with the PSU. Try not to use splitters if you can help it. Instead, use 1:1 molex/SATA adapters.

 

What I question is how do you balance drives among rails without knowing the total architecture of the power supply.

 

From what I read, the rails are usually divided up among,  Peripherals (molex/sata), motherboard & CPU connectors, PCIe connectors.

My perspective leads me to believe you can't really balance peripherals between rails, yet the advice of balancing per wire is very important, I would even say crucial considering the size of disk arrays we are  talking about supporting.

 

<snip>

 

There is a part of me that believes the multiple drive bays offered in todays market,  help alleviate the issue of current draw and physical connections.

I.E. I've seen 5in3's with 2 power connections, making me believe this suffices for physical foundation for the power draw.

 

Comments?

 

With the modular Corsair HX series, it's easy to balance among the rails since they have a diagram of which rails the different slots are using on their forums. With others, though, it's not quite as easy so going with a single rail PSU might be less of a headache. I'm inclined to agree with you on the 5in3 comments. I think some backplanes also have staggered spin up built-in so that helps reduce the load, too.

Link to comment

I definitely agree with all these points.

 

Where I am coming from this now is that with a single rail short of melting a cable you dont have to worry about ballacning load from a rail perspective. This is one less thing to worry about in the "build a perfect unRAID server" especially for n00bs. Im prepared to bet most users dont even think or read much about it at all so by recommending only single rails we will help more people without having to teach them a thing.

 

Also i think it is safest to recommend a PSU with a rating that can easily handle peak startup load. Staggering boot is just another thing for users to have to learn about and mess up.

 

Sure there are plenty of gurus here that will go the extra mile but thats not whom this thread is really aimed at.

 

Or put another way in the cost of a build the difference between a cheap potentially wont work supply and a higher end single rail will definitely work in any reasonable configuration is at worst a few tens of bucks.

 

 

Link to comment

With the modular Corsair HX series, it's easy to balance among the rails since they have a diagram of which rails the different slots are using on their forums. With others, though, it's not quite as easy so going with a single rail PSU might be less of a headache. I'm inclined to agree with you on the 5in3 comments. I think some backplanes also have staggered spin up built-in so that helps reduce the load, too.

 

Oh this is great news!!!! I bought a corsair HX650 recently!

Link to comment

This is one less thing to worry about in the "build a perfect unRAID server" especially for n00bs. Im prepared to bet most users dont even think or read much about it at all so by recommending only single rails we will help more people without having to teach them a thing.

 

Also i think it is safest to recommend a PSU with a rating that can easily handle peak startup load. Staggering boot is just another thing for users to have to learn about and mess up.

 

From what I'm learning the noob's are becoming much more educated thanks to this forum and community. Hat's off to y'all.

As far as staggering boot, that can be done in software with more modern drives. A script at startup could enable Power up in Standby.

No that this is the answer, but it's a method of assisting initial startup issues.

 

 

Link to comment

Oh this is great news!!!! I bought a corsair HX650 recently!

 

Perhaps you meant the HX620? You can find the diagram here. One of the rails is dedicated to the motherboard/CPU so you're really only left with 2 12V rails to play with but that should be good enough for dividing amongst a bunch of drives. :)

 

Yes, HX620... and considering there are 2 dedicated rails to choose from according to the forum link's diagram, I think I'll do fine.  36A (18A+18A) wiith loadsharing should make it easy to balance things out.  The calculator said a 520 would have sufficed for 20 drives, so I think the extra headroom will be fine. Thanks, that link was helpful.

Link to comment
  • 6 months later...

I realize this is an old thread, but since it was linked from the PSU Wiki page, I felt it would be best to post here.

 

I am researching PSU's for an unRAID server I am putting together and this thread made mention of using modular plugs.  But, PC Power and Cooling's website claims that modular PSU's are a BAD thing:

http://www.pcpower.com/technology/myths/#m3

 

What do you folks think about this?  Do you agree with this and should we only consider buying non-modular PSU's?

 

Thanks.

Link to comment
3. DON'T LOSE POWER WITH MODULAR PLUGS

 

Due to their look, convenience, and cost savings for manufacturers, modular plugs have become a popular power supply feature. Unfortunately, there has been little or no discussion of the impact of this feature on overall performance and reliability. The fact is, modular plugs limit power by adding to electrical resistance. The voltage drop can be as much as would occur in 2 feet of standard wire. Worse yet, modular plugs utilize delicate pins that can easily loosen, corrode, and burn, creating the potential for a major system failure. That's why professional system builders specify uninterrupted wire!

 

For convenience here it is.

 

Personally i dont care about this insertion loss. I would much rather have a neat install and especailly true with modern PSUs, I dont want 20 random cables cluttering up the place and massing up air flow.

 

Its easy to make claims about insertion loss but not all connectors are made equally.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.