mini nas power supply dilema.

PSUs: The source of DC power for all components in the PC & often a big noise source.

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corrsfan
Posts: 2
Joined: Sun Aug 05, 2012 2:52 pm

mini nas power supply dilema.

Post by corrsfan » Sun Aug 05, 2012 3:48 pm

Hello all,

Im all over the place on the best psu for me, and need some advice before i go do something silly.

Basically im changing my big system down to a wee system, its up and running using a frankenstien like mess of cables/adapters, but im not sure if its too close to the spec or not, to leave for too long before replacing with something better.

system currently is ;
asus p8h77-i, G620 cpu, 2 dimms, a tv card, 4 * samsung 1TRB f3 drives, 1 * ssd, 1 optical drive in a befenix prodigy case (loving this case btw)
i used my Antec tp 550w + power meter and it shows ~120w at post time, and 80w at load, 65 at idle.
Changed the PSU for the one in my other thermaltake itx system - its a 220w. shows slightly less power at load & idle, but same peak load @ post.

SO:
Do i assume that whatever happens i need to accommodate for 120W at idle, meaning that i cannot really go for anything less than say 150-160W assuming it runs at > 80% efficiency.

How do i know how much headroom i have on this current PSU? I gather than bulk of the load is on the 12V lines (which isn't being taxed) , but i dont want to overload the 3 & 5v lines with the drives as the specs look weak for this PSU, and im already running some sata extensions cables etc.

has anyone seen plates which allows for these sfx psu's to go into the normal atx spaces, if im persuaded to keep this ghetto rig as it is, until I look at upgrading my cpu...

HFat
Posts: 1753
Joined: Thu Jul 03, 2008 4:27 am
Location: Switzerland

Re: mini nas power supply dilema.

Post by HFat » Tue Aug 07, 2012 6:15 am

Is this your Antec PSU? http://www.silentpcreview.com/article712-page4.html
If so, based on your measurements your rig should be OK with a PSU that provides 100W. Of course it's also got to provide enough power on each line and so on. And you may want some headroom over that.
Powering up your hard drives is the main reason you couldn't use a weak power supply. I don't suppose your board has an option to power them up one after the other instead of all at once?

CA_Steve
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Location: St. Louis, MO

Re: mini nas power supply dilema.

Post by CA_Steve » Tue Aug 07, 2012 6:55 am

Just a note on calculating power...

If you measure 120W AC at boot, and your TP550 is ~79% efficient at this load (thanks for the review link HFat), then the PSU sees ~95W DC load (.79*120).

corrsfan
Posts: 2
Joined: Sun Aug 05, 2012 2:52 pm

Re: mini nas power supply dilema.

Post by corrsfan » Tue Aug 07, 2012 11:58 am

thanks for the suggestions, but even if it did support delayed spin up, id still feel uneasy as it will be using raid, so will be using > 1 drive at any 1 time.

I see the way you guys are thinking also with regards to the DC power shown , to see if the pico or true psu's should be ok for me also. I just wish samsung had put a sticker on the drives like my wd 2TB drive has that specified exactly how much power will be taken from each rail, but the samsungs arent exactly true enterprise grade kit, like the wd drive is.

Ill see what i can see PSU over the next week or so, but for now project mini me is going to run with the smaller psu, and look for a more elegant solution, as im not liking the cable management bolt on situation.

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