The Power Supply Thread


dgaschk

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I currently have an array with 16 7K2000 drives.  These are 7,200RPM drives but Hitachi shows the power at 2.0 and not three like has been suggested here for faster drives (should I believe Hitachi?).  I'm getting close to needing more space so I'm looking to replace the Antec case/PSU with a Norco 4224 and have every intent to max it out with 24 drives as soon as unraid supports that many.  I'm waiting for the next great sale on the 5K3000 drives and am trying to figure out the power requirements for the 4224 loaded with all these drives.  I'm leaning towards the CORSAIR CMPSU-750TX (http://www.newegg.com/Product/Product.aspx?Item=N82E16817139006).  With a single 60A rail it seems that this should do just fine, no?

 

Also could someone please clue me in on the difference between their normal PSU and the enthusiast line such as this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139021  It looks like it's justa $5 difference but I'd like to understand what the $5 gets you.

 

Both of the supplies you reference are from Corsair's TX line, the difference is that the first one is an older version of the unit, it's less efficient and performs worse.  It's still a very solid supply, but the TX750 V2 (the second one you linked) is a much better buy overall.  My feeling is that any price premium on the older unit is likely due to declining supply.

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  • 3 weeks later...

Anyone know how many amps the new 3TB drives require?  I'm just looking at future proofing.

 

Go to the manufacturer's websites and hunt around for data sheets. You could also try Googling it.

 

EDIT: The Hitachi 7200rpm 3TB drive requires 2A at startup, so I'd assume the Green version would require less than or equal to 2A.

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A good PSU for unRaid has the following:

 

1. Single 12 volt rail.  A subsequent figures refer to the 12 volt rail.

 

 

While I understand the logic to using a single 12V rail supply (no need for load balancing etc) is there any reason you can't use a quad rail supply? (as I have a spare lying around with I think about 18 amps on each rail)

http://www.shoppingsquare.com.au/p_2960_GreatWall_GW700SEL_700_WATT_TRUE_POWER_SUPPLY

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A good PSU for unRaid has the following:

 

1. Single 12 volt rail.  A subsequent figures refer to the 12 volt rail.

 

 

While I understand the logic to using a single 12V rail supply (no need for load balancing etc) is there any reason you can't use a quad rail supply? (as I have a spare lying around with I think about 18 amps on each rail)

http://www.shoppingsquare.com.au/p_2960_GreatWall_GW700SEL_700_WATT_TRUE_POWER_SUPPLY

Yes, typically only 1 of the rails is available for the hard disks.  The others are reserved for the CPU power, the PCIe connectors.   That would then give you basically 16 to 18 Amps of capacity to run the disks, fans, and in some cases, the motherboard too.

 

See here for an example of a supply I purchased, but knowing it suited my needs, since I intend to re-wire it:

http://lime-technology.com/forum/index.php?topic=6879.msg66778#msg66778

It is a 4 rail supply, with 1 rail used for all the disk connectors, but that same rail is shared with the motherboard connector too.

 

The problem is, with most multi-rail power supplies, YOU CANNOT LOAD BALANCE without internally re-wiring the supply and voiding your warranty.

If you are looking to power more than 5 or 6 disks, get a single rail power supply.

 

The supply you linked to is a two rail supply, odds are very high you have about 15  Amps capacity for disks.  (and likely not even that)

If both rails are actually 18 Amps in capacity, then even the 700 Watt rating is highly suspect.   2 * 18Amps * 12Volts = 432 watts.  That would indicate the 5 volt rail would need to have the remaining capacity?  But I highly doubt it has a 53 Amp rating...

 

Joe L.

 

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Hi

 

I just build a new server with a Supermicro X7SPA MB and 6 3TB disks.

The first psu I bought was a Coolermaster Elite Power 400 (RS400-PSAPJ3-EU) dual 12V and when I switch of the server it draw 10W.

Later after reading here I bought a Corsair Builder CX430 V2 (CMPSU-430CXV2EU ) single rail 12V and when I switch of the server it draw 30W. ???

Somebody know how thats possible.

 

Rob

 

Problem solved I bought a new measurment device the Cresta RCE 1106.

Power switch off 0W

Power switch on server off 2W

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Yes, typically only 1 of the rails is available for the hard disks.  The others are reserved for the CPU power, the PCIe connectors.  That would then give you basically 16 to 18 Amps of capacity to run the disks, fans, and in some cases, the motherboard too.

 

See here for an example of a supply I purchased, but knowing it suited my needs, since I intend to re-wire it:

http://lime-technology.com/forum/index.php?topic=6879.msg66778#msg66778

It is a 4 rail supply, with 1 rail used for all the disk connectors, but that same rail is shared with the motherboard connector too.

 

The problem is, with most multi-rail power supplies, YOU CANNOT LOAD BALANCE without internally re-wiring the supply and voiding your warranty.

If you are looking to power more than 5 or 6 disks, get a single rail power supply.

 

The supply you linked to is a two rail supply, odds are very high you have about 15  Amps capacity for disks.  (and likely not even that)

If both rails are actually 18 Amps in capacity, then even the 700 Watt rating is highly suspect.  2 * 18Amps * 12Volts = 432 watts.  That would indicate the 5 volt rail would need to have the remaining capacity?  But I highly doubt it has a 53 Amp rating...

 

Joe L.

 

,

Yeah it claims to have four rails on the casing which also seems suspect because that would be more like 850 - 900W. I'll check with a multimeter to see if the two hard disk rails are connected. I could always swap over the plugs on the PCIe connectors for Molex plugs and use them to power the hard disks as I won't be using a PCIe video card..

 

It is weird that they dion't split the hard disk connectors off more than one rail because according to Intel's ATX standard the maximum on any 12V rail should be 20 amps..., which means most single rail supplies do not comply with the ATX standard..

 

Thanks for the feedback Joe

 

John

 

 

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Hi

 

I just build a new server with a Supermicro X7SPA MB and 6 3TB disks.

The first psu I bought was a Coolermaster Elite Power 400 (RS400-PSAPJ3-EU) dual 12V and when I switch of the server it draw 10W.

Later after reading here I bought a Corsair Builder CX430 V2 (CMPSU-430CXV2EU ) single rail 12V and when I switch of the server it draw 30W. ???

Somebody know how thats possible.

 

Rob

 

Whether a supply is single rail or two rail or quad rail doesn't have a lot to do with it's efficiency. It really comes down to the design, cooling and other factors. Check out http://www.jonnyguru.com/ for excellent reviews on a lot of popular supplies. Best to do this pre-purchase. For standby efficiency particularly pay attention to a PSU's efficiency in that 0-10% range. There are now three easy standards as well Gold, Silver and Bronze... with gold being the best  :)

 

Better still purchase one of hte recommended supplies on this forum.

 

30W seems like a lot at standby...

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... according to Intel's ATX standard the maximum on any 12V rail should be 20 amps..., which means most single rail supplies do not comply with the ATX standard.

 

IIRC, the ATX2.2 standard specified a current limit for any one rail, but the 2.3 standard changed that.

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Yeah it claims to have four rails on the casing which also seems suspect because that would be more like 850 - 900W. I'll check with a multimeter to see if the two hard disk rails are connected. I could always swap over the plugs on the PCIe connectors for Molex plugs and use them to power the hard disks as I won't be using a PCIe video card..

 

It is weird that they dion't split the hard disk connectors off more than one rail because according to Intel's ATX standard the maximum on any 12V rail should be 20 amps..., which means most single rail supplies do not comply with the ATX standard..

 

Thanks for the feedback Joe

 

John

 

Your math is incorrect.  You don't figure out total +12V wattage on a multi-rail PSU by taking the rail amperages, multiplying them by the voltage in question and adding them together.  The PSU label will have information for the total combined wattage.  Basically the reason for this is that a multi-rail PSU is really just a single rail PSU with the current split up for OCP, so just like a single rail PSU it can only pull so much wattage.  Each rail can go up to a certain maximum current before tripping OCP, but the supply as a whole cannot sustain all of the rails running at their maximum OCP rating.

 

And PeterB is absolutely correct, after ATX 2.3, there is no absolute over current limit.

 

I do wish someone would make a more server friendly consumer PSU.  Having molex/hard drive power spread out over multiple rails would be nice.  I mean, sure single rail makes things easy in the sense that you know there's no chance of tripping the OCP without just plain overloading the supply, but if you get a short and you're running a, say, 750W PSU, something is going to fry, and I wouldn't put my money on "not the drives".

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next month I need to get the last few things for my build I have almost the same build as this http://lime-technology.com/forum/index.php?topic=12822.0 I am planning on from now on to get 3tb drives. what about this for a psu http://www.corsair.com/power-supplies/modular-psus/professional-series-gold-2/ax850.html

 

Assuming you're running all green drives, that's probably more power than you need, but there's nothing wrong with it.

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next month I need to get the last few things for my build I have almost the same build as this http://lime-technology.com/forum/index.php?topic=12822.0 I am planning on from now on to get 3tb drives. what about this for a psu http://www.corsair.com/power-supplies/modular-psus/professional-series-gold-2/ax850.html

 

Assuming you're running all green drives, that's probably more power than you need, but there's nothing wrong with it.

 

the only other options are 650,750 or 1200 watt I am looking for a efficent psu that can handle when all drives are running and is efficent at the converting

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Hi

 

Did some more testing on the CORSAIR Builder Series CX430 V2 430W.

If I switch off the PSU main switch it slill draws 18W ???

Main switch on 30W.

Power on the system with disks spin down 45W.

I thought it was a bad supply and bring it back and get a new one.

This one exact the same.

I think when you switch off the supply it should draw nothing.

Can you guys test it on the same supply there are more users that use this power supply.

 

Rob

 

Problem solved I bought a new measurment device the Cresta RCE 1106.

Power switch off 0W

Power switch on server off 2W

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@Rob ,

 

seems to me there is a power leakage somewhere or a faulty measuring. 30 watts, even with the power button from the power supply off? that seems not normal to me.

 

I have the CX430 (before v2) and a cresta RC-1106 watt-meter

 

http://www.cresta.nl/index.php?Itemid=2&option=com_zoo&view=item&category_id=25&item_id=138〈=nl

 

http://www.kijkshop.nl/product/21159/295-1276/merkenshops/cresta/cresta-energiekostenmeter-rce-1106/

 

My Un-Raid server is just having his montly parity check,, but will measure mine with power button off and come back to you on this tommorow.

 

What kind of measering device / watt-meter do you use?

i read that there a lot low budget watt meters on the consumer-market which have huge differences in measuring wattage comparing actual usage. especially with lower wattages

 

example actual use 50 watts ( by an professional labo device) Brand A says 70 watts ,, and Brand B says 25 watts.

 

Reading from your e-mail adres you're from NL , so you can read this.

 

http://nl.hardware.info/nieuws/14165/testresultaten-energieverbruiksmeters

 

English:

 

http://babelfish.yahoo.com/translate_url?doit=done&tt=url&intl=1&fr=bf-home&trurl=http%3A%2F%2Fnl.hardware.info%2Fnieuws%2F14165%2Ftestresultaten-energieverbruiksmeters&lp=nl_en&btnTrUrl=Translate

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Hi Rembro

 

No fault here I use the Brennenstuhl BN-PM230 and it reads switch off 18W switch on 28W I also measured with a Fluke 87V.

It was measured with 235V switch off 70ma (16.45W) and switch on 120ma (28.2W).

Think its weird but got a new supply with exact the same measurements.

 

Rob

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Hi Rembro

 

No fault here I use the Brennenstuhl BN-PM230 and it reads switch off 18W switch on 28W I also measured with a Fluke 87V.

It was measured with 235V switch off 70ma (16.45W) and switch on 120ma (28.2W).

Think its weird but got a new supply with exact the same measurements.

 

Rob

Unless your power supply has a physical switch that interrupts the power conductor from the cord to its electronics, it is not really "off" when you press the momentary button on the PC case.  It is still supplying the standby 5volt supply that is used to power the LAN chipset and the electronics used to monitor the power pushbutton on the case.

 

Unfortunately, most consumer electronics works the same way.  Very few have an actual "power switch" these days.  (and if it has any remote control that can turn it on, it cannot really completely be turned off)

 

The only difference you'll find is how much current they draw when "turned off" waiting for you to put the button on the server to them on.

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@Joe - could not write it down better,,  if you al count that ''standby'' usage together in a today's household most people will be surprised what the yearly cost would be.

 

@Rob

 

I just did the test with my CX430 (non V2)

 

server turned off : power supply button on = between 1 and 3 watt

server turned off : power supply button off = 0 watt

 

this is weird comparing with your test results

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Hi Rembro

 

I have other supply's laying around with the same results as yours accept the corsair and because I have had 2 of them I think its normal on the other hand when I switch the server on it's the one with the best efficiency .

 

Hi Joe understand that but I think 30W with power switch on and server off is to much these days.

 

Rob

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Hi Joe understand that but I think 30W with power switch on and server off is to much these days.

I agree, sounds high.  You should calibrate your wattmeter, even if crudely, by plugging in a known wattage electric lamp.

A 40 Watt incandescent bulb should read near 40 watts on your meter.  If it reads somewhere near 70 or 80 watts, then the power supply reading might not be right either.

 

It sounds like a very inefficient supply if it is going to be off most of the time.  30 watts when off is a lot, even if you get an employee discount from your electric company. (no, I do not work for the power company, but I think I must look into it... my last bill was over $300 dollars.)

 

 

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