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Woody
12-12-2001, 05:03 PM
Heya all... i am getting a new server soon.. and was wondering what sort of power supply i would need

here are the specs:

AMD Duron 900
Cheap Graphics card
Epox 8k7a+ (RAID)
10/100 Netgear Network card
Onboard sound

it is going to have 8 IDE HDD's in it most likely the following:
4 x 60GB
2 x 40GB
2 x 20GB

would a 300watt power supply be large enough to power all those HDD's??

Andy
12-12-2001, 05:15 PM
personally, i would go for 350W-400W or if you budget allows, 450W

Woody
12-12-2001, 05:17 PM
what about dual Power Supplies??

any way to run them without getting a special case?

sKuLLsHoT
12-12-2001, 06:55 PM
a case like the DTK u and I have are great for dual PSUs and there is perfect space at the top for a second, u just needa do a little bit o dremel work

Woody
12-12-2001, 07:04 PM
and how do u hook it up to work properly????

Mr. C
12-12-2001, 07:44 PM
Heres a nice article at VirtualHideout (http://www.virtual-hideout.net/guides/atx_psu_mods/index.shtml)

Onyx
12-12-2001, 08:19 PM
300W sounds like its plenty enough.

Albinus
12-13-2001, 07:44 AM
Let's look at some figures:

Firstly, hard drives only really strain the PSU when they spin up. Always allow the worst case power draw, which is usually around 1 ampere on both the 5V and 12V rail (check the drive to make sure). This equals 17 watts of power, multiplied by 8 = 136 watts.

The Duron should be chewing around 45 watts, my guess as I'm too lazy to look it up in AMD's whitepapers :D Total so far is 181 watts.

The motherboard should take around 25 watts, the memory around 20 watts (to be safe). We're up to 226W.

The graphics card, if it's "cheap" (like a GeForce2 MX/200) should draw around 5 watts (they don't chew much) and the network card should be the same. So the total is just under 250 watts.

So the answer is yes - 300 watts will be enough, just make sure to choose a quality power supply such as Enermax, but if you can't afford one of them AOpen make rather nice PSU's as well :) Cheaper PSU's, although rated for 300W, may not take that as a sustained load.

I hope this helps Woody :wave:

Woody
12-13-2001, 11:16 AM
yeah does help alot :).. will just get a 300 watt power supply :) that should be cool :)

sKuLLsHoT
12-13-2001, 09:36 PM
one problem with your math i think...

a visit to the IBM site has revealed that the drives(i think all Woody's drives are IBM?), on startup use approximately 2A loading on the 12V line, so thats 24W of power per drive, and no specs on the 5V line, but i will go with the assumption that it would be a max loading of 1A (doubt that) and that should equate to29x8 which is 232W

now, a visit to the AMD site shows us a list of recommended PSUs, i have used the list for the 1600+ bcoz u said u were gunna get that so go here AMD PSU Rec's (http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_869_1039^4038|48_ATX,00.html) and look at the huge list... i would like to point out that they actually state the PSU manufacturer rating (ie Aopen 300W) and the "actual" combined power capacity (ie Aopen 300W=200)

if u take the individual max amp ratings on each v-line available on the PSU do the math on the usable power with those figures...u can work out the true value of the PSU... now the power usage of the 1600+ is something in the ball park of 50W at a guess ( i know theres a util u can get somewhere that can calculate the power usage of a CPU but i can't find it now...)

now lets take the rough 50W from the cpu, add the other 50W allowance for system devices, and hell, we have hit a grand total of 232+50+50 = 332W used at a startup, now, using your Aopen 300W "Rated" PSU, u r 132W over the true capability of the system when u turn the thing on... okay, so thats turning it on only, but what if we say that the average use we have the equivalent of 7 idle HDs(6 - 8W each) and one full-operation HD (24W) thats (7x7) 49+24=73W for HDs plus 50W for a CPu and 50W for the system, thats 173W, so Then, the lovely 300(200)W psu is happy, until of course u start using several HDs simultaneously...

i think i have done a full course on this subject now!

if anyone could post a link to one of them Power calcs for CPUs that'd be great...

But anyways, get somethin better than 300W, its the bare minimum PSU usually, with AMD...sure it may keep pluggin along as is if u got it, but the life of it is going to be crap all...and a PSU that craps out can be rather ugly, even with the fuses and protection they nearly all have...

This has been another insightful story from sKuLLsHoT!

Albinus
12-17-2001, 11:03 AM
I was basing my HDD judgements on 7200RPM Western Digital drives - maybe they use less power than IBM ones? :?:

I stand by my calculations - and AOpen PSU's are generally rated 20% below what they are capable of. My 300 Watt model is running a 1.7GHz Pentium 4 (over 80 watts there), 4 Hard Drives (2 of them Quantums = more power), every adapter card slot full, overclocked AGP card and 6 fans. The PSU copes admirably.

As for the power calculations - refer to the CPU datasheets provided by Intel and AMD on their websites - under Thermal data.

And don't forget RAID drives (Promise ones at least) have staggered startup to prevent overloading the PSU - SCSI cards are like that as well. This simply turns the RAID drives on one at a time to minimise bogging down the PSU :)

Onyx
12-17-2001, 06:42 PM
I dunno bout anyone else, but I for one have never come across a single case of someone's PSU not being strong enough to sustain their system.

All the high wattage PSUs (400W, 500W+) are just playing on people who think bigger is necessarily better.

For instance, I don't know of anyone having a 1.0 litre car that wasn't powerful enough to get up a hill. No matter how steep it was.

sKuLLsHoT
12-17-2001, 08:49 PM
in response to that....i can say that I HAVE seen as well as heard of instances where the PSU doesn't cut it.. the problem is a lot of people end up passing it off as a faulty m/b or video card, seen it all too often...

its moreso a case of a PSU carking it after going too hard too long, and thats danger in any system....i am convinced that 300W will only be bare-minimum sufficient, and i myself would only use a trusted brand's 300W rating, brand-trust is a more personal thing though, i do urge people take a look at the AMD recommended PSU list i linked earlier...

JealousMidget
12-17-2001, 09:15 PM
I dunno bout anyone else, but I for one have never come across a single case of someone's PSU not being strong enough to sustain their system.

All the high wattage PSUs (400W, 500W+) are just playing on people who think bigger is necessarily better.

For instance, I don't know of anyone having a 1.0 litre car that wasn't powerful enough to get up a hill. No matter how steep it was.

Actually, I had that problem, not too long ago. The PSU didn't explode or damage anything or do anything dramatic. It just could not handle the load. After I overclocked, there wasn't enough juice to keep everything running, so I would get booted out of games, once my vidcard started sucking power. That was an "extreme" case, cause I had a 145W PSU and replaced it with a 350W Enermax. But it is still relative, the more devices/toys you have drawing power, the more power you need to keep everything happy. It all balances in the end.

cheers :beer: :beer: :beer:

RDR
12-17-2001, 09:33 PM
in response to that....i can say that I HAVE seen as well as heard of instances where the PSU doesn't cut it.. the problem is a lot of people end up passing it off as a faulty m/b or video card, seen it all too often...

its moreso a case of a PSU carking it after going too hard too long, and thats danger in any system....i am convinced that 300W will only be bare-minimum sufficient, and i myself would only use a trusted brand's 300W rating, brand-trust is a more personal thing though, i do urge people take a look at the AMD recommended PSU list i linked earlier...

I have seen cases where a 300w power supply couldn't cut it - but size was not the problem - in every case it was a cheapo generic PS, when it was replaced with a good quality 300w the problems went away

Albinus
12-18-2001, 05:17 PM
I have seen cases where a 300w power supply couldn't cut it - but size was not the problem - in every case it was a cheapo generic PS, when it was replaced with a good quality 300w the problems went away


That's what I'm trying to push here - a cheap 300 watt PSU will probably **** itself, whereas a good one from the likes of AOpen or Enermax will cope quite fine :thumb:

Morgan_Lander
12-19-2001, 01:16 AM
But still, 8 IDE devices? They're not SCSI but I still think a 350 watt is the minimum he should have. 400 watts is good. Beyond that is overkill IMO, but it won't hurt. ;)

My 2cents.:shoot: :grenade: :snip:

ct_
12-19-2001, 01:53 AM
I dunno bout anyone else, but I for one have never come across a single case of someone's PSU not being strong enough to sustain their system.

All the high wattage PSUs (400W, 500W+) are just playing on people who think bigger is necessarily better.

For instance, I don't know of anyone having a 1.0 litre car that wasn't powerful enough to get up a hill. No matter how steep it was.



well, i had a 300 watt jobber in my last case with all the same drives i have now

it ended up frying 2 hdd before i figured out the problem was they were being underpowered while in heavy use (that was the very LAST thing it could have been, btw)
and this was a good 300w psu

i upgraded to a 400w enermax and i have no problems now

situation:

i just got myself an OLD gateway server case, 6 ext bays, 4 internal, and space to hang another 5 bay cage :)

problem is the psu that came with it

this sucker is BIG, and i mean HUGE!
2 1/2x the size of any standard psu you can get these days BUT it's only 250watts

i have a 200 and a 250 watt AT psu lying around collecting dust, so i'll epoxy them together, cut a big enough hole for the fans and the plugs in the back (not like it will take much cutting anyway!) and screw them to the case
i'll combine the two power switches to the origonal on/off switch
and i'll still have an inch over top and 2" below the combined PSU to play with

so, using the 250 for the main hdds, the board and the cpu fan, and the 200 for everything else

question:

will that be enough to power the 4 maxtors(on pci card), the WD(ide), the scsi card (zip250), the usb(camera, printer, game pad, zip100), idecdrom, scsicdrom, idecdrw, idedvd(with dvd decoder card), cpu (amd k6-3+ 450), board (gigabyte ga-5ax) and the rest of the system bus ?


let's assume i'm burning a cdr(1), listening to MP3's(2), surfing/chattin' online(3), sending email(4), downloading anything i can find @ a nice speed(5), all while serving FTP/http(6) and managing/moving files round(7) ?

all of which happens frequently enough at the same time as to make this a valid question, and i'm not including sending stuff to the printer or playing a game (which takes 100% cpu everytime) when i'm not surfing

(1) idecdrw drive taking data from the same drive as:
(2) most of the mp3's and a lot of space for temp storage
(3) mostly cpu power, some hdd as i go to new sites
(4) all email is stored on yet another hdd, and i sometimes sned quite large files
(5) main hdd for downloads
(6) spread all across the drives
(7) same thing as 6

i rarely see more than 15- 19% cpu at a time for more than a few minutes and it's usually under 10%
sure, it spikes to 100%, but that never lasts more than a minute or so