[MRD]

I am looking to get a new power supply for a fileserver. It will be running as many as 10-12 hard drives, a few optical drives, no graphics card (onboard, headless). Hard drives draw off both the 12V and 5V rails, although as I understand, mostly off the 12V, especially on spinup. My question is really what I need to look for in a psu, and if the 5V rail is a concern. Most power supplies now supply one or more 12V rails with a lot of current, but not so much on the 5V.

I will probably also use a number of expansion cards (RAID, SATA, network) which all draw off the 5V I believe (at least for pci, not sure on pci-e). The cpu right now will be a single core sempron (am3). I may upgrade to a multi core, higher wattage AM3 for backup and compression purposes, as well as software RAID 5 parity calculations.

Finally, I will be using a lot of fans (larger ones, 120's and 140's) to keep the drives cool. I think that will pull mostly off the 12V so it shouldn't be an issue.

Can I split SATA power adapters? I've heard some bad things about using molex to SATA power adapters. Any thoughts there?

I've been looking at the Corsair TX650 on sale at the egg. Will this work ok? Only 8 SATA connectors. 650W should be fine, as long as the 5V can handle it.

[thideras]

I run the Corsair HX620 in my server and that is "way more than enough". It power 9 3.5" 1tb hard drives and 3x 2.5" SAS enterprise class drives. In addition to that, it powers a Phenom I quad core along with two RAID controllers. This will power the entire server full of drive (21) with any other hardware I can throw at it.

If you get the HX series, you could always make your own cables or have someone make them for you. It is actually extremely simple and what I did to my file server. The plugs are proprietary, but the pins are the normal ATX 24/8 style.

Beyond that, you can use the molex->SATA converters, I haven't heard of any issues with them.

[MRD]

So am I overthinking this? Should I just use my existing 400W FSP ?

What would you say would be the least expensive PS (or wattage if you don't know models) that would be a safe bet? (Assume a high quality brand like Corsair or Antec.)

Do you recommend the HX over the TX just because of the modular cabling and hence the ability to add lots of SATA connectors, or do you prefer it for other reasons?

[thideras]

I honestly can't answer the wattage question. All I know is that OW said the 620 was overkill for that many drives when I asked about it.

I prefer the HX because I can make my own custom cables for the unit. It makes my server cleaner on the inside.

[beenthere]

http://www.extreme.outervision.com/p...ulatorlite.jsp

[thideras]

Originally Posted by beenthere

http://www.extreme.outervision.com/p...ulatorlite.jsp

This calculator is a joke (aka: useless). I just entered my server in and it told me 781 watts. I'm running a 620 watt power supply and I know I have a ton of room left in it.

My entire rack doesn't even take 781w. I'm using a kill-a-watt to measure.

[Trap05]

I think if you're 500w+ and 80+ rated I think you'll be fine. Personally I'd go with something that has a 12cm fan and has enough sata connections to suit your needs. I don't see why the 650tx wouldn't be a solid choice.

[beenthere]

Originally Posted by thideras

This calculator is a joke (aka: useless). I just entered my server in and it told me 781 watts. I'm running a 620 watt power supply and I know I have a ton of room left in it.

My entire rack doesn't even take 781w. I'm using a kill-a-watt to measure.

If you enter the correct data it will tell you the peak load that your system will see and the minimum recommended PSU. Corsair and others also have less sophisticated PSU calculators.

[thideras]

Originally Posted by beenthere

If you enter the correct data it will tell you the peak load that your system will see and the minimum recommended PSU. Corsair and others also have less sophisticated PSU calculators.

It doesn't matter if that was peak or not, my power supply is not capable of putting out 780 watts for any length of time. The calculator has always been way off and is an extremely poor way to find out how much wattage something needs unless you don't care about saving money.

[MRD]

Was going to get that 650tx, but new egg cutbthe rebate from 30 to 10 last night, so I went with the 550vx. Not modular, but I think it should be fine. My case can accommodate 2 psu's anyways if I really got desperate.

[madhatter256]

Just add the amps the HDDs draw in both 12v and 5v. Try to be below 20% of the maximum amps the PSU can dish out.

[ratbuddy]

Originally Posted by madhatter256

Try to be below 20% of the maximum amps the PSU can dish out.

What? Why? That'll just result in poor efficiency. You want to be around 50%.

[EarthDog]

Originally Posted by madhatter256

Just add the amps the HDDs draw in both 12v and 5v. Try to be below 20% of the maximum amps the PSU can dish out.

Originally Posted by ratbuddy

What? Why? That'll just result in poor efficiency. You want to be around 50%.

You are exaggerating with the word poor. Here are some examples of a couple common PSU's. Their % difference, IMHO, hardly makes it poor in a 50% vs 80% situation. Its literaly a couple % efficiency difference.

http://www.jonnyguru.com/modules.php...tory3&reid=169

http://www.jonnyguru.com/modules.php...tory2&reid=126

[ratbuddy]

Originally Posted by EarthDog

You are exaggerating with the word poor. Here are some examples of a couple common PSU's. Their % difference, IMHO, hardly makes it poor in a 50% vs 80% situation. Its literaly a couple % efficiency difference.

http://www.jonnyguru.com/modules.php...tory3&reid=169

http://www.jonnyguru.com/modules.php...tory2&reid=126

A 24/7 server drawing about 250 watts gives a cost savings of $20 a year (where I live, $.21/kwh) when run on an 85% PSU compared to 82%. Yes, it's just "a couple % efficiency difference," but it does add up.

Going by his "under 20%" suggestion would mean running a 1000+ watt PSU for a 200 watt load

[EarthDog]

Heh, I would imagine he meant what I was thinking....at least how I read it, that to load a PSU up to 80% (20% of the max. You are saying 50%. That is what I was comparing, not 50% load vs 20% load where there actually may be a bit more of a difference depending on the PSU.

Im not sure that changes the results though. If one is hurting for $20 that bad, then other issues need handled first.

Regardless, 'poor' would not have been the adjective I would use in either situation. Maybe 'slightly less' is what I would have used IF he was thinking my way.. I see why you read it like that (it was written that way!!)

[MRD]

My energy efficiency will suck anyways, I'm getting a UPS too. Really I am just worried about performance for this one, not energy efficiency.

Mostly up and running now. Too bad the 2gb of ddr2 that I got from the egg (gskill) were defective. For now running an old 512 stick.

8 drives so far and no problems, more to come. Out of SATA ports though and trying to figure out how ot add more without bottlenecking speed or breaking the bank. Any ideas would be welcome. Don't need hardware raid / fakeraid.