power supply and scsi drive question

[quakefiend420]

how many 9.1gb 10k rpm scsi drives could i theoretically run off of a fortron 230W PSU?

the psu is:
14A 3.3+
22A 5v+
8A 12v+

the psu is a fsp235-60gn

i will be powering 2 80mm fans, a celery 533 and mobo with onboard everything, 2 sticks of PC133, 1 30gb ide hdd, 1 60gb ide hdd, and an adaptec 2950 pci scsi controller card, and as many 9gig 10k scsi drives as possible

the hdds will use the 3v and 5v rails more than the 12v right?

this is my file server, i'm just curious how many drives i can run on this psu and stay stable...basically what can i get before i need a new psu...i have an antec true430 in my main rig...might put it in the server and get a new one for this box...just trying to see if thats neccessary

thx in advance

 

[CalvinHobbes]

This may help:
http://www.pcpowercooling.com/maxpc/index_cases.htm

 

[ribbon13]

HDD's use 5v and 12v rails. Which it uses more really depends on the model. SCSI's likey use more 12v. probably 5w each. assuming 5x9=45 using over half your 12v rail...

 

[quakefiend420]

Originally posted by: CalvinHobbes
This may help:
http://www.pcpowercooling.com/maxpc/index_cases.htm

nifty...thx

 

[quakefiend420]

ok using that calc calvin posted this is what i have

5w nic
20w scsi card
40w ide drives
6w fans
40w mobo,cpu
20w ram

131w no scsi drives

since the cpu and mobo used to run off of a 100w max microatx psu that had 2 amps on the 12v i'm assuming they dont use a lot of juice

it says to multiply by 1.8 since todays systems draw a lot form the 12v rail...but this is a pretty old box...so it would pull more on the 3v and 5v correct?

how do i determine how much wattage is on each rail?

i guess i'm wondering where to go from here...since i'm pulling 130w now should i assume i have another 100 or so to play with or what?

 

[ribbon13]

you completely ignored me there, but I'll be nice and give you a hint.
Volts (12v rail) * amps (8) = Watts (96)
your 12v has 96 watts capacity.

 

[quakefiend420]

Originally posted by: ribbon13
you completely ignored me there, but I'll be nice and give you a hint.
Volts (12v rail) * amps (8) = Watts (96)
your 12v has 96 watts capacity.

ooohhh, i see...sorry its early

looks like the psu is rated a bit conservatively...

12v is 96w
5v is 110w
3v is 46w

so i should shoot for loading each rail 70% at max right?

when it says a device pulls 20w from the 3.3v and 5v rail should i assume a draw of 10w per rail, or 20w per rail, or what?

 

[ribbon13]

I have high end 15krpm SCSI's and they consume almost zero 5v idle..

for startup, I'd say 5w on 5v each and 10w on 12v each.

Better yet, specific model?

 

[quakefiend420]

68 Pin
Quantum Atlas 10K 3.5 Series 9.1 GB u160/m
REV00
Dell Pulls, Dell PN 004160U-12541-991-00BS

EDIT: i have 5 of those that i would like to use, its really not a whole lot of storage space...i just want to play with scsi as i have never had any hands-on experience with it


EDIT2: damn thats a hell of a rig you're running!

 

[ribbon13]

http://maxtor.com/_files/maxtor/en_us/d...ions/atlas_10k_scsi_specifications.pdf

I'm good neh?

Power Specifications
Voltage Requirement (V) +5V DC ±5%;
+12V DC ±5%
Typical Power Draw (W, Idle)
SCSI
8


Typical Current Draw (A,
Operating)
5V 0.50
12V 0.65

Peak Current (A on +5V/+12V)
SCSI 0.80/2.70

 

[quakefiend420]

awesome!

thx for all the info, looks like i may need to use this antec 430 in the server and get a new one for the main rig, eh?

 

[ribbon13]

You can get a PCP&C silencer 470 for $99

 

[quakefiend420]

is that a 24 pin psu? i was thinking of getting one of the new ones so i wouldnt need to upgrade it for a while...

 

[ribbon13]

Yep it is. Comes with a 24->20pin adapter too.
http://www.pcpowerandcooling.com/produc...pplies/ultra_quiet/silencers/index.htm

 

[quakefiend420]

what about using a seperate psu to power the drives temporarily?

 

[ribbon13]

I've done that before. You just have to short the PSON pin with a ground on ATX psus.

 

[quakefiend420]

Originally posted by: ribbon13
I've done that before. You just have to short the PSON pin with a ground on ATX psus.

thx...i'll google that in a min

 

[Zepper]

You could probably run about 4 SCSI drives off that Fortron. Remember, most Fortrons are rated at continuous rather than max Watts. IAC, you will want to set the SCSI host adapter's BIOS settings to stagger the drive startup as 4 drives would pull about 12 to 16A if they all started up at the same time. Stagger start will spread out the startup loads. Too bad the same can't be done with the IDEs as those are the only other items in your rig that use 12V
.bh.

 

[quakefiend420]

Originally posted by: Zepper
You could probably run about 4 SCSI drives off that Fortron. Remember, most Fortrons are rated at continuous rather than max Watts. IAC, you will want to set the SCSI host adapter's BIOS settings to stagger the drive startup as 4 drives would pull about 12 to 16A if they all started up at the same time. Stagger start will spread out the startup loads. Too bad the same can't be done with the IDEs as those are the only other items in your rig that use 12V
.bh.

if the controller card supports it that would be cool...i'm kinda thinking i might just trade the drives for a large ide drive and skip on all the scsi stuff...since i would probably need to replace the psu to run all of them stable...

 

[Zepper]

Most HAs support 'stagger start' because starting 15 or more HDs at once could rupture just about any known PSU. The drives can also be individually set to delay start. So in the worst case you can set three to delay start so that you'd have only half the startup load at one time. But stagger start is best and you don't have to mess with locating the drive jumpers.
.bh.