TWO Power Supply Hookup

Hi Gang!

I hope someone has time to offer some technical advice. I have been pondering a better power arrangement for a PC using a cube case that can physically accept TWO power supplies.

I came across this web page (http://www.speedy3d.com/articles/case_mod_p3/) describing the use of a 2nd power supply (as opposed to the 'redundant' style arrangement). I would love to hear comments on his technique, as it desrcibes a simple DC switch or relay between the 'sense' and 'ground' wires on the ATX connector of the 2nd PS. I always though the use of a PC Power Supply required a minimum load, (i.e., we cannot use them for general bench power). If the author is correct, these ATX supplies must have some kind of automatic loading.

1) Are these ATX supplies that flexible? Or better yet, is there such a thing as an auxillary (back-loaded) PS that is appropriate for stringing all the stuff we like to pack into a computer case?

Anyway, that leads to the rough plan I had. I am wary of the accumulative effect of the spike from the simultaneous Power-On of everything when the power switch is thrown. I envisioned a more balanced situation with two supplies, one going on first, the 2nd following perhaps 5 seconds later.

PS#1
----
4 x 120mm fans (cube case)
CPU Orb Cooler
Video Cooler
USB Bay
Digital Doc III
Floppy Drives
LS-120 Drive
Removeable HD Cart
other case spot fans, lights, etc

PS#2 (delayed)
--------------
Motherboard
PIII-1000
PCI: nVidia GeForce2
PCI: SB Live
PCI: Adaptec u160
PCI: Modem
2x128 DIMMs
SCSI 7200 HD
ATA 7200 HD
Plextor CDR

This seemed like a logical division of power (startup spike). I figured on a simple switch to fire up #1 (sense line to ground), this would get the fans up to speed, light up some LEDs to say everything is ok, and the Digital Doc shows temps on the critical components (in this case BEFORE they are even powered up). The second PS supplies all these critical components which as you see have substantial requirements.

Then, I thought, maybe a relay might be nice. If there is such a thing as a 10 second relay, it could connect the sense line of PS #2 to a 12v line in #1.

2) Is there any appropriate relay that someone may know of?

3) What do you all think of this strategy in general?

4) What are the best recommended PS manufacturers?

Perhaps it would be easier for everything here to just be shucked off a giant 450w PS with tons of Y-cables, but I still am wary of the giant spike from the total intitial draw. Or, am I worried for nothing?

5) BTW: Is there any known problem with powering up floppy and CD drive motors BEFORE powering up the mainboard that they are connected to? I suspect this would be bad for IDE and SCSI drives, or am I wrong again?

Thanks in advance to this group!
Sarah McIntyre
BladeFlash^aol.com

Where is this "cube case" you mentioned? First thing I can think of, is two power supplies- twice the probability of failure and twice the heat output. Why not just buy a large 450W supply? If you've gone all out on the components, a proper power supply should have been in your initial plans. I'm not trying to talk you out of it, just trying to get a grip on the thought process.

As for the accumulative effect of the power spike, there shouldn't be one because you're powering different components with different ps's. Besides, I would imagine most ps's use capacitors or some other circuitry to negate the large spikes.

The best power supplies: www.Antec-inc.com and www.pcpowercooling.com.

I'd like to know what you ended up doing either way and how's it working, so you can email me privately if you'd like.