Instructions on how to "connect" two PSUs for a single syste

[CharmedLover84]

Hey all.

 

I've been thinking about it for a while and I finally came to a decision, in the event I do get SLI (which I'm thinking about after the three monitor failure, selling my 8800GTX and getting two 8800GTSs instead), that I will need to wire-in a secondary PSU to help power my system and keep my volt-rails running at acceptable power rates.

 

Anyone know of any good guides on how to do this fusing process?

[radodrill]

The simplest approach is to use a relay to turn on the second PSU when the firs comes on.

 

Using a 12V SPDT relay; just connect the +12V power (from molex) of the first PSU to the coil of the relay; then connect the Gnd of the second PSU to the relay's com connector and the PS_on (green) lead to the NO connector of the relay.

 

Once the first PSU comes on; it'll immediately bring the second online as well.

[CharmedLover84]

::blinks:: If I weren't so PSU-illiterate that woulda made more sense. I know it would have. LOL

[radodrill]

I've attached a sketch to illustrate the necessary relay connections.

 

Note: the PS_on is the green connector on the 20/24 pin power connector; shorting this to ground turns on the PSU; so that's what you'd use the relay for. When there is power across the coil it'll close the switch and turn on PSU#2.

[CharmedLover84]

::blinks:: I think I'll wait for a step by step guide that's for stupid people.

 

I know how to hotwire a PSU to run without anything plugged in but a liquid setup to get the air out of the tubes, but what you're talking about is a little over my head.

[radodrill]

Radio Shack Cat# 275-241 would work well for this application.

 

1) connect com and NO (Normally Open) pins of the relay to pins 15 (GND, black) and 16 (Green, PS_on) of the secondary PSU's ATX connector (same pins you'd use to hotwire the PSU)

 

2) connect the coil between the 12V (yellow) and Gnd (black) lines of a molex (IDE power) or floppy connector of the primary PSU.

 

3) done

 

 

What this does is: when PSU1 is turned on, the relay's coil is energized; throwing the switch from the NC (Normally Closed) to the NO connector, thus completing the circuit to hotwire PSU2.

[soundx98]

There is a big long thread over at OCF http://www.ocforums.com/showthread.php?t=8...light=Dual+PSUs

Personally, I'd start looking at a new PSU with the power you need.

If either of the "tandem" PSUs goes it can take a lot of expensive equipment with it.

[Guest Lancer33]

i have been running 2 PSU's for some time and agree with soundx98. Get one of the 1kw supplies that are now out. Less hassles, fewer total wires, and probably less cost depending on what unit you go with.

[soundx98]

"Back in the day" PSUs like the PCP&C 850W ran around $469.99.

Hardly chump change.

And some of the early freaks with huge SLI video card and HDD requirements NEEDED to put a couple of supplies together.

Nobody is singin' that song no more.

Just go do it right the first time if you need more juice.

[taowulf]

I have a nifty connector that would let me do this, it has a pass through for the power connector to go to the mainboard and a two wires with a connector for the second PSU...the problem is that the connectors are 20 pin, not 24.

 

I have looked in vain for a 24 pin equivelent, but have been unable to find one.

 

I just wish I knew where I picked this one up....I tend to collect cables, connectors and so on.

 

I will try to find it when i get home and post a pic.

[CharmedLover84]

That would be ideal, all I need the extra power for really is a second video card, although if I get two 8800GTSs I don't think this PSU would have too much of a problem. And even if it did, I could just sell it to a friend and get a 760 Watter from Fortron that's the same thing with higher Amperage. We'll see.

[thefabe]

Then why not just buy a 5.25 bay psu for the video card? something like this http://www.newegg.com/Product/Product.asp?...N82E16817153037