Question about using PicoPSU to spin just HDs 24x7

gourdo_1 · Post by **gourdo_1** » Tue Apr 24, 2007 12:02 am

Ok, so I went and bought a PicoPSU-80W without fully doing the math. Since the mini-box support folks haven't answered my inquiry, I thought maybe some SPCR readers would have some knowledge.

Here's what I want to do:

Run a monster OCed gaming rig with a Corsair 520HX. It will sit in standby mode throughout most of the day (so as not to rack up an enormous power bill leaving on 24x7) but with Wake-on-LAN when I need to access it remotely.

However, due to bad past experiences with dying HDs, I try *not* to spin drives up and down much at all, and do not want to risk cycling the drives a couple dozen times a week.

So, I've decided to run my three SATA 3.5" HDs separately off a PicoPSU (not RAIDed BTW) in the same case. I plan to modify the PicoPSU with a simple toggle switch as the 520HX will control the motherboard. The PicoPSU will run only the drives along with a 120mm fan 24x7 so as to keep their operating environment as cool and consistent as possible.

Here's the thing, I believe I'm well within the amp and watt margins when the drives are already spinning, but on the rare occasion that I do start them up, I don't know if the picoPSU will be able to handle the spike of 3 drives all trying to spin from rest at the same time.

Here's what mini-box claims the PicoPSU line can handle (I'm getting PicoPSU-80):
http://www.mini-box.com/site/ComparisonChart.htm
In summary:
5A on the 5V line
3A on the 12V line
80W max

Here's what the hungriest HD spits out (Raptor 150GB 10k RPM):

12 VDC
Read/Write 470 mA
Idle 375 mA
Standby 18.75 mA
Sleep 18.75 mA
5 VDC
Read/Write 875 mA
Idle 938 mA
Standby 488 mA
Sleep 450 mA

Power Dissipation
Read/Write 10.02 Watts
Idle 9.19 Watts
Standby 2.66 Watts
Sleep 2.48 Watts

Assuming, worst case, 3 of these are connected, I would be looking at:

5V rail: 3x 938mA = ~ 3A
12V rail: 3x 470 mA = ~ 1.5A
Power: 3x 10W = ~ 30 Watts
+ 120mm fan = a couple watts?

So I *think* I'm ok according to this data. But what's not listed is what the startup power requirements are for this drive. I have no idea what kind of power it takes to start this thing up and whether the PSU is smart enough to start each one up in serial...

Can anyone confirm I've given enough headroom?

P.S. Yes, I already have offline backup for important documents. I realize this plan is not a substitute for a good backup strategy!

andyb · Post by **andyb** » Tue Apr 24, 2007 5:47 am

I thought that the PICO PSU only actually output 3.3v and 5v, and the 12v was just a pass-through from the Power Brick that puts out 12v to start with. If I am right then those 12v numbers are BS, as its the brick thats doing the work.

Andy

gourdo_1 · Post by **gourdo_1** » Tue Apr 24, 2007 12:31 pm

Hmmmm, that's news to me. Is this true? Doesn't say anything about that at the mini-box website...

Devonavar · Post by **Devonavar** » Tue Apr 24, 2007 12:34 pm

I don't foresee any problems. I use 25~30W per drive as a startup estimate, which gives you 75~90W. Theoretically, I think it's possible you might overdrive the brick during startup, but the spike will probably be too brief to trigger a shutdown. My feeling was that the PicoPSU was pretty robust, and could withstand brief spikes over its capacity.

I'd make sure you do the research about how the running drives will interact with a sleeping motherboard though. I'm not sure whether the drives will automatically reconnect to the disk controller when the system wakes up ... though if hot plug is supported I suppose it should work...

jojo4u · Post by **jojo4u** » Tue Apr 24, 2007 2:34 pm

What's the name of your employed drives? And what mainboard do you have?

floffe · Post by **floffe** » Wed Apr 25, 2007 11:07 am

And also, will the drives spin just because they have power, or do they need the disk controller to tell them to spin up? I'm pretty sure you can't keep it from telling them to spin down when you power off the mobo...

Devonavar · Post by **Devonavar** » Thu Apr 26, 2007 12:42 pm

It depends on the drive. Most drives will keep spinning when powered whether or not they have a data connection. I've seen a few Hitachi drives that require a data cable to start though...

gourdo_1 · Post by **gourdo_1** » Mon Apr 30, 2007 7:07 pm

floffe wrote:And also, will the drives spin just because they have power, or do they need the disk controller to tell them to spin up? I'm pretty sure you can't keep it from telling them to spin down when you power off the mobo...

ALl the drives I've ever used in the past spin automatically with power... but it looks like I'm outta luck this time. My Raptor does not spin up without a data cable. So, I'm out $75 for this picoPSU that just came today.

bexx · Post by **bexx** » Mon Apr 30, 2007 11:38 pm

Check the jumpers on it, usually that is an option to only spinup when it gets some command from the controller.

Usually if any jumper has the word power in it try the opposite of what its set at.

bexx · Post by **bexx** » Mon Apr 30, 2007 11:42 pm

actually i thought i was too lazy to look it up but...
http://wdc.custhelp.com/cgi-bin/wdc.cfg ... 1071171477

That one jumper `controlled spinup via spinup command per ata standard' sounds like something you don't want. Try either taking hte only jumper off or putting it on the pins closest to the molex power connector.

gourdo_1 · Post by **gourdo_1** » Tue May 01, 2007 7:18 pm

bexx wrote:That one jumper `controlled spinup via spinup command per ata standard' sounds like something you don't want. Try either taking hte only jumper off or putting it on the pins closest to the molex power connector.

On the Raptor, I put a jumper on pins 1-2, then 3-4, then 5-6, then 7-8.. no luck. My older IDE drive spins up fine each time with application of power.

I'm stumped.

HexiumVII · Post by **HexiumVII** » Sat May 05, 2007 12:38 pm

A cheap way is use an ac adapter that does directly to molex. They come with the IDE to USB cheapo adapters so you can run hard drives outside of the box to testing and stuff. They are usually around $15ish and includes everything. A lot cheaper than a pico + the 90watt ac adapter you need. The one i have provides 2A to the 5 and 12v and uses about 6-8 watts for standard 7200rpm drives. Cheapest place i can think of is dealextreme/kaidomain, maybe frys or look up the deals forums for specials.