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Dual power supplies?

Z

Zinn

Guest
The fan in my friend's Antec 420 is dying so he ordered a new one... I figure I could replace the fan (easy) ...

so that got me to wondering, could I jump the ATX connector and run a dedicated power supply JUST for my 6800GT? My current one isn't up to the task of overclocking either video or CPU... but if I had TWO power supplies... Heh, I know it would look rediculous having an external power supply, but at least then I could determine what this machine would be capable of if i plopped down the money and got a PCP&C (which I plan on eventually)

Of course, if it's not possible due to cross-loading requirements or whatever I won't try it. Just thought I'd throw the idea out.
 
When I read your idea, i though it was great. But then i saw what you wrote about cross-loading and that got me thinking about how it might be a bad idea. If it were me, I would spend the money on a new power supply rather than to wreak my video card and have to spend even more money.

But the choice is up to you,

...Dan
 
That wouldn't work. You'd load up just the 12V and you'd see it drop really fast. It's the whole reason I got into this "power supply testing" thing. I tried load testing power supplies with 12V light bulbs, but found that ALL of the power supplies I tested were out of spec with only a 10A load on them! Because SMPS's need a fairly even load on them that corresponds with their specs.

The only power supply I've seen NOT do a big drop on the 12V is the Ultra X-Finity 600W because the 12V all comes from a seperate power supply that produces ONLY 12V.
 
a rudimentary tutorial

a little more indepth info on dual or modular PSUs

cut and paste 101
----------------------------------------------------------------------------------------------------------
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(3 is slightly outdated now see gee's post 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
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Well I was hoping it would be as simple as jumping the ATX connector and plugging in... looks like that won't be possible due to the loading requirements. Maybe I should load it up with neon and LEDs (kidding). Thanks for the info JohnnyGURU and Ice Czar. Instead of risking my video card and/or motherboard with this mod I will buy a better supply when the time is right (G70 release, maybe)

I wish I had a crummy older Pentium 4 1.8 box to test this sort of thing on... I really don't want to fry my primary rig. Oh but there is this dual P3 server sitting next to me collecting dust... I wonder if my boss would miss it :rolleyes: ;)
 
I run a second 250W AT PSU in my system. The PSU powers four of my hdds. Because the HDDs don't care when the computer turns on, its not an issue as far as syncing, so I set the AT psu switch to on, used some electrical tape to insulate all the metal on it, and stuffed it, as well as the AT mobo connectors inside the PSU. So now I have a compact PSU that fits inside my case(SuperLANBOY) right behind the HDDs and my system is stable and overclocks better than before. Before I went PCIe, I also had the PSU powering the video card. I didn't run into any sync issues with that either.
 
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