Two psu on one graphics card

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Johnnam93

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So I am currently building a computer that has two power supplies (400W and 350W) since I dont have the money to buy a new one.
My graphics card requires two 6pin pcie connectors but both of my power supplies only have one each.

So my question is, will it be okay for me to use one 6 pin pcie connector from each psu as long as I equally distribute the rest of the parts to each psu?

My other option is to get an adaptor from molex to 6 pin pcie but I would rather not spend money if it is not necessary.

The graphics card is a evga GTX560ti.
 
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Putting a "Frankenstein PSU" together that way is not likely to work well since the PSUs lack proper load-sharing circuitry. You will either end up with the PSU having the stronger 12V rail taking all the 12V load or the PSUs going into oscillation if the PSUs start "chasing" each other: the stronger PSU's output voltage rises, takes load off the weaker PSU, the stronger PSU's output voltage starts sagging, the weaker PSU starts picking up load again, rinse and repeat.

Depending on your luck, the results may not be pretty... instead of needing a proper PSU for $50-70, you may end up blowing up all your components including both PSUs and needing a whole new PC instead including a proper PSU you should have bought in the first place.
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Titan
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Putting a "Frankenstein PSU" together that way is not likely to work well since the PSUs lack proper load-sharing circuitry. You will either end up with the PSU having the stronger 12V rail taking all the 12V load or the PSUs going into oscillation if the PSUs start "chasing" each other: the stronger PSU's output voltage rises, takes load off the weaker PSU, the stronger PSU's output voltage starts sagging, the weaker PSU starts picking up load again, rinse and repeat.

Depending on your luck, the results may not be pretty... instead of needing a proper PSU for $50-70, you may end up blowing up all your components including both PSUs and needing a whole new PC instead including a proper PSU you should have bought in the first place.
 
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i7Baby

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I hope they're both good quality - from tiers 1, 2a or 2b of http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html

You're going to find that from moment to moment the connectors aren't giving out the exact same voltage with 2 psu's - especially 2 with large variations in voltage. This isn't going to prolong component life. If the variations are large enough it'll show up as eg frame stuttering, pixelization, overheating, poor performance, etc.
 
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Johnnam93

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Does the Lian Li dual psu adapter not regulate the load on each psu properly? I thought if I used one psu on my graphics card and the other on everything else it would be okay..

Thanks for the opinions though! I'll look into other psu's and try to buy one later then and put this project on hold.
 
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Johnnam93

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I have a evga GTX560ti
 
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Titan
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That is a very hypothetical "should."

Best case, whichever PSU has the highest output voltage will take most of the load since the other PSU will not be providing any power until wiring losses bring the "stronger PSU" outputs down to the "weaker" PSU's level, which is not going to be anywhere near even between the two PSUs unless they are almost perfectly matched..

Worst case, the two PSUs will bounce load between each other, go into oscillation or some otherwise unstable operating mode - assuming the PSUs even needed any external "help" with that, destroy each other and possibly take the rest of the computer with them.
 
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Johnnam93

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Yeah my main question was whether or not using one from each power supply was a bad idea. Then my other solution was to get an adapter for a molex to 6 pin so that only one psu was powering my graphics card. But from the looks of it, most of yall agree that I should avoid that and just get a new psu haha
 
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Titan
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There are just too many ways this could potentially go wrong.

It MIGHT work... it would probably work at least somewhat. But if it does not, you could lose everything.

Not worth the risk.
 
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