Multiple computer PS?

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Guest

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Hey everyone.

I have an old P3, RAID card, and a bunch of HDs laying around. I'm
worried about power requirements, as the biggest spare PS I have is
250W... is it possibly to use multiple PS in a custom built case?
Would I have to wire the power supply outputs in parallel so that all
power + ground are common, or can I use one to power the motherboard
and a HD or two, and the other to power the drives on the RAID?

Just curious... I have a lot of spare parts and a lot of time on my
hands.

Joseph
 

Philo

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Joseph Davis wrote:
> Hey everyone.
>
> I have an old P3, RAID card, and a bunch of HDs laying around. I'm
> worried about power requirements, as the biggest spare PS I have is
> 250W... is it possibly to use multiple PS in a custom built case?
> Would I have to wire the power supply outputs in parallel so that all
> power + ground are common, or can I use one to power the motherboard
> and a HD or two, and the other to power the drives on the RAID?
>
> Just curious... I have a lot of spare parts and a lot of time on my
> hands.
>
> Joseph

do *not* wire the supplies in parallel

you can use a second supply to power your harddrives if you wish.
just get a switch which allows you to turn on both supplies at the same time
 
G

Guest

Guest
Archived from groups: alt.comp.hardware.homebuilt (More info?)

I would think that a 250w PSU would be sufficient, I used to have a P3
running all the time with a 250w and had 3 hard drives and 2 cd rom drives
and it was fine. I only went to above 250w when I got my athlon cpus.

doughnut



"Joseph Davis" <george1879@charter.net> wrote in message
news:04el70dtpc2qnnmohia6kksccj75g1b5an@4ax.com...
> Hey everyone.
>
> I have an old P3, RAID card, and a bunch of HDs laying around. I'm
> worried about power requirements, as the biggest spare PS I have is
> 250W... is it possibly to use multiple PS in a custom built case?
> Would I have to wire the power supply outputs in parallel so that all
> power + ground are common, or can I use one to power the motherboard
> and a HD or two, and the other to power the drives on the RAID?
>
> Just curious... I have a lot of spare parts and a lot of time on my
> hands.
>
> Joseph
 

overlord

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Aug 29, 2001
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Archived from groups: alt.comp.hardware.homebuilt (More info?)

I ram a K2-6 AMD 450 with 8 drives and a CDROM off a 220watt PS.
It was a quality PS tho. Used to know a link to a schematic to splice
2 PS together but lost it. You don't need to do it with that P3 tho.

My PS is going out so it's running the system and fans. I have an identical
case with an AT PS in it sitting next to it with the cables running over to power
the drives.

On Mon, 12 Apr 2004 15:11:26 GMT, Joseph Davis <george1879@charter.net> wrote:

>Hey everyone.
>
>I have an old P3, RAID card, and a bunch of HDs laying around. I'm
>worried about power requirements, as the biggest spare PS I have is
>250W... is it possibly to use multiple PS in a custom built case?
>Would I have to wire the power supply outputs in parallel so that all
>power + ground are common, or can I use one to power the motherboard
>and a HD or two, and the other to power the drives on the RAID?
>
>Just curious... I have a lot of spare parts and a lot of time on my
>hands.
>
>Joseph

~~~~~~
Bait for spammers:
root@localhost
postmaster@localhost
admin@localhost
abuse@localhost
postmaster@[127.0.0.1]
uce@ftc.gov
~~~~~~
Remove "spamless" to email me.
 
G

Guest

Guest
Archived from groups: alt.comp.hardware.homebuilt (More info?)

On Mon, 12 Apr 2004 15:11:26 GMT, Joseph Davis <george1879@charter.net>
wrote:

>Hey everyone.
>
>I have an old P3, RAID card, and a bunch of HDs laying around. I'm
>worried about power requirements, as the biggest spare PS I have is
>250W... is it possibly to use multiple PS in a custom built case?
>Would I have to wire the power supply outputs in parallel so that all
>power + ground are common, or can I use one to power the motherboard
>and a HD or two, and the other to power the drives on the RAID?
>
>Just curious... I have a lot of spare parts and a lot of time on my
>hands.
>
>Joseph

There may be a vast difference between a generic 250W and a good
name-brand. Which you have may determine it's true output capability, and
further, how it's output is distributed... with a bunch of old HDDs you'd
be better off with a power supply having a lot of 12V amperage. If the
system's bios has a setting to delay for "n" number of seconds, that might
help, give the power supply more time to spin-up the multiple hard
drives so they're properly detected.

You don't necessarily need a custom built case for two power supplies,
most any full tower will do if you stack the 2nd PSU above the first
(and of course cut out the needed hole(s) for fan, power, screws).

You cannot simply wire the two unit's output in parallel. They regulate
themselves based on voltage monitoring, at a minimum on the 5V rail.
There may be a way to reverse engineer them and provide a good current
sharing method beyond hooking them together with isolation diodes as that
would be rather lossy. What you could do is use the 5V output from one
and the 3V from another, and have the drives distributed amongst both
units. Easier (and probably plenty good enough) would be to simply use
the 2nd power supply to power only the drives and any misc offboard parts
(like case fans).

Assuming both power supplies are ATX, you could connect both unit's PS_ON
leads (pin 14, usually a green wire) together then they both come on
together, but that's based on the assumption that the motherboard can
'sink the combined current... I have done this and had no problems but it
is still a consideration. An alternative might be to use a power rail
from one of the unit's to flip a relay which connects the other unit's
PS_ON line to ground. Then there is the manual method, a simple switch to
flip every time you power on the PC (by pressing the "regular" case
switch) and then also having to turn off the 2nd power supply when the
system is powered down, which to me seems like an undesirable situation.
 
G

Guest

Guest
Archived from groups: alt.comp.hardware.homebuilt (More info?)

In article <04el70dtpc2qnnmohia6kksccj75g1b5an@4ax.com>,
george1879@charter.net says...
> Hey everyone.
>
> I have an old P3, RAID card, and a bunch of HDs laying around. I'm
> worried about power requirements, as the biggest spare PS I have is
> 250W... is it possibly to use multiple PS in a custom built case?
> Would I have to wire the power supply outputs in parallel so that all
> power + ground are common, or can I use one to power the motherboard
> and a HD or two, and the other to power the drives on the RAID?
>
> Just curious... I have a lot of spare parts and a lot of time on my
> hands.
>

/shudder

Cheaper and safer to buy a slightly larger, quality
power-supply should the existing 250W not meet your
needs.
 
G

Guest

Guest
Archived from groups: alt.comp.hardware.homebuilt (More info?)

I always found it rude to post a follow up thanks reply to one
specific poster, when you get lots of good input from a couple of
different ones. You guys rule!

I'm a cheap bastard with a couple of different cheap 200-250W PS
laying around. I can't see spending for a good quality unit when
using two in tandem (not parallel) would keep the load light and not
tax them. It's not my main machine, so a little less reliability is a
non-issue.

Thanks,

Joseph
 
G

Guest

Guest
Archived from groups: alt.comp.hardware.homebuilt (More info?)

>I'm a cheap bastard with a couple of different cheap 200-250W PS
>laying around. I can't see spending for a good quality unit when
>using two in tandem (not parallel) would keep the load light and not
>tax them. It's not my main machine, so a little less reliability is a
>non-issue.

I'm not sure how it would work if they were used in tandem. Will you run some
devices off different supplies from each other?!

As somone mentioned in this thread, it's not good to parallel them without
serious consideration to load balancing, etc. You can, in certain cases,
parallel transformers, supplies, etc but it may take some glue circuitry or
mods. Not something to be taken lightly.

Michael