How many hard drives can I put on my 500 watt power supply (safely)?
Question by foucachon: How many hard drives can I put on my 500 watt power supply (safely)?
Here’s the context. I’m running an older computer as a server. I have a 350 watt power supply running inside the chassis JUST for the CPU, video card, internal fans, motherboard, etc.
I have an additional power supply DEDICATED to 5 hard drives and 1 fan. It’s running fine right now, but I would like to add some more hard drives – possibly as many as 3-4 more.
Will my 500 watt power supply power up to 8 hard drives (plus one 14mm fan) just fine? Should I get ANOTHER power supply for the additional drives ?
Thanks!
(PS – if you’re wondering how I’m fitting all those drives, they’re actually external on this rack: http://www.amazon.com/Sans-Digital-HDDRACK5-5-Bay-Organizing/dp/B001LF40KE/ref=sr_1_1?ie=UTF8&qid=1339093657&sr=8-1 ). I have Sata cables running from the motherboard, out of the back of the computer, and to this rack).
One of you requested a photo š
https://www.facebook.com/photo.php?fbid=10150680218634712&l=f8cccca336
Best answer:
Answer by Menard K
You should have a wattage number for any given device that you intend
to connect, simply add up the wattage numbers and see what you have.
GOOD LUCK
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I’d love to see pictures of this thing. It sounds like a “good hack” (he said with admiration).
The problem is that a power supply rating (e.g.: 500 Watts) doesn’t tell you how the power is split between the various voltages. Manufacturers design them to supply 3.3, 5 and 12 Volts in proportion to the usage in a typical configuration. That’s usually lots of power at the lower voltages to supply the CPU and video chips, and relatively little power at 12 Volts to supply one or two hard drive motors and a couple of fans.
So, you really need to look at the detailed specs for your hard drives, and your power supplies. You could run out of current on the 12 Volt line long before you hit the power supply’s total power rating.
EDIT: 8-JUN-12: Thanks for the picture!
I’ve done a bit of “modeling” to get you a better answer. Picking a power supply and hard drive more-or-less at random from NewEgg, the specs show:
Power supply: CORSAIR Builder Series CX600 V2 600W ATX12V v2.3 80 PLUS Certified Active PFC Power Supply,
+3.3V@25A, +5V@25A, +12V@40A, -12V@0.8A, +5VSB@3.0A
40 Amps on the +12 Volt rail – that’s far more than I expected to see. And that’s the line that spins the drives and fans. Good.
Hard drive: SeagateĀ® BarracudaĀ® 1 TB, ST1000DM003
Startup Power (A) 2.0
Operating Mode, Typical (W) 5.90
Ignoring the 5 Volt line for now (which won’t be much on a hard drive, anyway), that’s about 0.5 Amps to maintain a hard drive in operation, but 2 Amps to spin it up from zero to 7200 RPM.
Leaving some margin, this power supply could easily serve a disk farm with 16 of these drives. If you had some kind of sequencer to power-up the drives one at a time, it would handle far more.
You’ll have to perform this analysis with your own equipment in mind. But it’s looking pretty good from here.
September 9th, 2012 at 1:59 amHard drives don’t use much power at all, so you should be safe.
HOWEVER
It really depends on what your power supply puts into the different rails.
September 9th, 2012 at 2:22 amSomeone ran 25 2 TB drives off of 1 power supply, along with all the rest of their components, and it was 1500 watts..