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Discussion Starter · #1 ·
Hello,


I am hoping I may be able to elicit a few suggestions about suitable power supplies for large 10 disk+ servers.


I know there are quite a few of you out there who are running the likes of the Norco 4020 with 20+ disks, my own system is a little more modest with 12 drives, but my power supply is starting to struggle, the system intermittently drops disk when the array is under load yet the disks when checked are fine. As the power supply is going on for 6 years old and is rated at 500W I am thinking that the problem is the power supply, specifically the 12V and 5V lines which power the Molex and SATA power connectors. The supply I have is a single rail type, and I think it is struggling to supply sufficient current to these lines to power my HDD's.


What are the preferred power supplies for those of you running large servers?


The rest of my system is quite modest with an Asus A8N-SLI Deluxe motherboard with a S939 Athlon 64 3800+ CPU and 2GB Ram with a Radeon X800GT graphics card. My RAID card is an LSI 84016E. I think the problem is that this power supply was purchased when this machine was my main PC and has been running the machine 24X7 through it's itterations as it transitioned from desktop to house wide server.


Do you favour a single high power line or split rail configurations and which brands do you find the most resilient for 24X7 operation?


Your thoughts and suggestions would be much appreciated.


Best wishes,


Dave
 

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I'd get a $20 kill-a-watt meter and find out what your system is actually drawing. 500W continuous will have a significant impact on your electric bill, 360kwh per month ($36/mo if your rate is 0.10 per KWH) just for the server if in fact it's pulling the full 500W. Most computers don't pull as much as most people think.


I'm a big fan of 80+ supplies for computers that run 24/7, they also tend to be built better. Feel the weight of one vs. a normal supply of the same wattage.
 

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Discussion Starter · #4 ·
Hi,


Thank you for your suggestions.


With regards to the Kill A Watt, I do have a meter like that on my system and it's consistently only pulling around 230W, so theoretically my current supply should be fine, as it's 500W rated, hence me thinking it's either failing, or it's the load on one of the lines which is exceeding it's rating.


As far as efficiency is concerned, I'm happy to report that here in the UK most quality PSU's are rated to over 80% efficiency. I am intrigued as to whether any supply with this label is rated to 80% + efficiency at any current draw, or whether the PSU efficiency drops off as the currents demand is lowered. I would suspect it's pretty linear but I am not completely sure. I was thinking of buying something with plenty of capacity in mind, 700W or above, but then if it's only loaded at around the 250W level would it still be as efficient as, say, a 400W?


Bighick:-


I will definitely check out Antec and OCZ, I currently use an Antec Twelve Hundred case so I know just how good their products are, glad to hear the quality is maintained in their PSU range. I've just been on the site to calculate my likely system load, it suggested the minimum supply for my current system should be 554W with a potential loading, assuming the server has a full complement of 16 drives, of 646W, so realistically I think I need to be looking at 700W+ based on this sites recommendation to stay safe.


Thanks and best wishes,


Dave
 

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The 80% rating is normally with a load at least 20% of the power supplies rating. If the PC is PULLING 230W the power supply is only outputting 80% of that or 184W. Any ATX 80+ supply is going to be at least 400W these days so you will have enough power no matter what you get. Your 6yr old supply could have some failing capacitors and that may explain the dropouts.
 

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Power supplies are not the same as amplifiers, where "headroom" is a good thing.....
Running a PSU consistently at >75% is BETTER in terms of efficiency of the PSU. Will it kill the PSU sooner? Who knows! The point is that you could run that PSU at
 

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Quote:
Originally Posted by kapone /forum/post/18268918


Power supplies are not the same as amplifiers, where "headroom" is a good thing.....
Running a PSU consistently at >75% is BETTER in terms of efficiency of the PSU. Will it kill the PSU sooner? Who knows! The point is that you could run that PSU at
 

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Quote:
Originally Posted by analogueaddict /forum/post/18268043


I do have a meter like that on my system and it's consistently only pulling around 230W, so theoretically my current supply should be fine, as it's 500W rated, hence me thinking it's either failing, or it's the load on one of the lines which is exceeding it's rating.

Your second theory is far more likely. The PSU may be rated for a total of 500W, but if you're exceeding the amp limit on any one rail, the total is irrelevant. If you do replace your PSU, go for one with a single 12V rail.
 

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Discussion Starter · #11 ·
Hello,


First let me start off by thanking all of you who took the time to contribute to this thread and help me with my dilemma.


I have made a decision on the supply, and I have settled on the Corsair HX650 semi modular PSU. Why? First off the rating should cover me for pretty much anything I want in the future, it uses a large diameter fan (120mm) and uses double ball bearings, increasing longevity and making it quieter, plus the fan is a thermostatic control type, so it speeds up as it gets hotter and slows when it gets cooler, the cables are modular, so I don't have an armada of PCIe graphics card power cables all over my system when I don't need them, and I can add SATA and Molex connectors to the PSU as required, the cables are also flat so they will be easier to run and allow me to layout the insides of my case with better airflow, it is also very efficient with 80plus certification and it is still efficient when lightly loaded. Finally it comes with a 7 yr warranty, and I don't think Corsair would give this warranty if they weren't confident it would perform at full rating for over 7 years.


OK, it's expensive, but given the value of my time to put all my media into my server in the first place, I'd rather pay a bit more and know my server and it's disk array are going to be reliable.


I hope I've made the right decision, and I'll report back once the PSU is installed (over the weekend).


Best wishes,


Dave
 

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I dont know if you ordered it or not but you might want to check out that site I mentioned to see how they feel about it and compare it to others. I know it will rank high but for the money you probably should make sure its the best in that price bracket. They do no wrong on that site.
 

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I was going to suggest a Corsair 550W with a single 12V power rail. I've read of people running 16 drives of one of these.


Figure on requiring about 2A per drive on the 12V rail plus about 5A extra to run the motherboard, assuming a newer low power CPU is used (65W model). If you've got a 95W or 125W CPU then add an extra 10A. This is still fairly conservative because it is only the power-on or spin-up drive current draw and not a continous draw. Also, the newer drives seem to be lowering the power-on or spin-up current draw.


So, for 12 drives allow for at least 29A and possibly up to 34A on the 12V rail. A good 550W supply should be capable of 40A on the 12V rail.


230W is actually pretty high. I'd say 10W for each drive and 50W for the motherboard is typical of new parts, measured at the power supply input. So, 170W would be a good number. I'm not sure if you've got extra losses in the old power supply or the components. It's likely a bit of both.



The thoughts about efficiency at lower power draw are true to a point. I did change the cheap case PS in my mini-ITX HTPC to a power brick with an open board power supply. The power I measured with the Kill-a-Watt meter dropped from about 50W to 38W at idle.


Quote:
Originally Posted by Servicetech571 /forum/post/18289015


If you are only pulling 230W look at this supply:
http://www.newegg.com/Product/Produc...-17139008-LC3A


$37 after rebate and free shipping with promo code EMCYPYX36

That's the one I use in my server. I plan on connecting 8 disks to it but with a lower power motherboard it could run up to 12 disks and even maybe a few more if using newer low power drives.


Peter
 

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Quote:
Originally Posted by JoshDorhyke /forum/post/18290312


I was going to suggest a Corsair 550W with a single 12V power rail. I've read of people running 16 drives of one of these.


Figure on requiring about 2A per drive on the 12V rail plus about 5A extra to run the motherboard, assuming a newer low power CPU is used (65W model). If you've got a 95W or 125W CPU then add an extra 10A. This is still fairly conservative because it is only the power-on or spin-up drive current draw and not a continous draw. Also, the newer drives seem to be lowering the power-on or spin-up current draw.


2A per drive! not a chance.



WD Green only use 7.4w while seeking 4.0w at idle, thats less than 1A/0.5A per drive. W=A x V
 

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Any hard disk will pull up to 30 watts for a few seconds when spinning up. That is why they have solutions to stagger the spin ups when starting up large disk arrays.


BB
 

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Quote:
Originally Posted by Servicetech571 /forum/post/18267793


I'm a big fan of 80+ supplies for computers that run 24/7, they also tend to be built better. Feel the weight of one vs. a normal supply of the same wattage.

Don't ever include weight of a PSU in your assessment of quality. Many manufacturers actually include heavy chunks of metal inside the PSU casing for the sole purpose of adding weight to evoke the illusion of quality; some of the better units available are actually quite light.


I second the recommendation of the jonnyguru.com site mentioned above, it's the definitive source for all things PSU. You'll get excellent recommendations in the forums there from true enthusiasts.
 

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Quote:
Originally Posted by Mr_Mike_P /forum/post/18291017


2A per drive! not a chance.



WD Green only use 7.4w while seeking 4.0w at idle, thats less than 1A/0.5A per drive. W=A x V

Up to 2A is the possible power-on draw. Did you bother to read two sentences further because you even quoted that part?


It's annoying when you explain it, yet someone still only reads about 5 words into the first sentence of your explanation and then stupidly go off...


Funny thing is I looked at the Seagate site again and they list the start current of the ST31500341AS as 2.8A which is higher than the current for any drive they posted before. When I looked a few months ago all their drives were a maximum of 2A. Oh well, all the LP drives are still listed at 2A.


And finally, I'm an electrical engineer so I certainly don't need you explaining to me how P = V x I.


Peter
 
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