how to set up two power supplies...

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chameleoneel

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ok, so, I'm going to be running SLI in about a week and even though my power supply will work fine for SLI, I want to run two power supplies if possible. say, one for the mobo and video cards and one for every thing else, or maybe one for the video cards and one for the mobo and everything else, but basically, how would I set it up so that both power supplies would turn on at the same time? because only one can physically plug into the board, so how could i get my other power supply in the "loop" so it starts with the first one? also, even if i can get it to work, is this a good idea? what do you guys think?
 
One way to do it is with a small DC relay. Connect a yellow and a black wire from the master power supply to the coil, and connect a green and a black wire from the slave supply to the contact.

Why bother with the second supply? You said yourself that one would work for your SLI rig.
 
i want to do it because i've read about many people having problems with sli rigs, stalling, stuttering, glitches, only to solve them by buying a rediculously expensive, better powersupply. so instead, why not use a power supply to power the mobo/cpu/ram/ maybe one videocard, and another power supply for harddrives, optical drives and the second video card. and besides, i have two power supplies, i would rather not spend tons of money on a pc power and cooling power supply.
 
davidhammock200 said:
Mobo & video cards must be on the same PSU or you risk damage to both. ;)
Click to expand...

A prudent precaution



my "stock" dual PSU answer
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

a rudimentary tutorial for ATX dual PSUs
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synch 2 PSU each as a seperate bus

1. Hardwired (what a CMStacker's adapter does)
2. With a relay

or employing a shared bus Like a redundant PSU

1. with resistors
2. with mosfets
3. with diodes (Single Source Fault Tolerant Power Systems)

(3 is slightly outdated now see gee's post > http://hardforum.com/showthread.php?t=776885)

I ran 2 hardwired 400 watts and a large RAID array for 3 years without issue on one of my boards (Abit KR7A)
however it may have been a contributing factor in the death of another board (ECS whatever :p )
though Im not at all sure about that

not running them synchd however certainly corrupted the hell out of the array :p
eventually switched to a Zippy Emacs MR3-6450P N+1
with considerably less total wattage but plenty for what was actually required
with 32A on the +12V rail for the drives and considering the mobo's VRM was powered off the +5V
---------------------------------------------------------------------------------------------------------------------------------

for hardwired thats

between the 2 PSUs its
green to green (POW_ON \ power on)
black to black (COM \ ground)

and on just the second PSU
grey to black (Power Good to COM\Ground)
 
ok, thanx for the info guys! now, does anybody know...is it ok to start hardrives before the mobo itself starts? cuz i was thinking that i could put all fans and optical drives on the second power supply, then i could flip on my cooling before the computer actually starts, and i might as well offload all of the drives onto that power supply too, so can this be done?
 
can be done yes,
corrupt the holy hell out of your filesystem ...yes :p

thats exactly why you synch the PSUs
you can likely get away with it a few times, but eventually its going to be an issue
 
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