Question Using 2 psu's to power nvidia gtx 550ti

[GregC1982]

Hi guys, so a few days ago my Corsair CX750M power supply had burnt smell and fan noise so I turned it off. Yesterday I turned it back on because I needed something off my computer and then the PSU completely died.
I've emailed Corsair and have yet to receive any response. This PSU has a 5 yr warranty and I'm on year 3 so they "should" replace it no problem.

In the meantime, I had to put my original psu back in and take out my Nvidia GTX card. Went to play Vanilla wow and can only get about 18 fps so that's gonna suck lol

I went and looked in the Nvidia box and found I had a 6 pin connector for the card which has 2 - 4-pin moeller connectors going into a 6-pin connector which feeds the Nvidia. It's used when you PSU doesnt have a dedicated 6 pin. Basically you just plug the 2 4-pin connectors into the 12v rails and then it's combined into the 6 pin which goes on the Nvidia card.

My question is;
Can I use 2 PSUs together?
1 that is in my pc now, < 265w max 12v rail, and 2nd PSU that is 12v < 245w max on it's 12v rail?

I was thinking outside the box saying, well connect 1 end of the 4-pin to one PSU in the computer, and setup the other PSU outside the computer with nothing running off of it except to connect the 2nd 4-pin connector to it.
Results = 1 PSU feeding the computer + Nvidia card and the 2nd PSU feeding only the Nvidia.

diagram:
https://drive.google.com/file/d/17b6UOARV2_YiXVdBvuh6DGrSWtedXcSY/view?usp=sharing

 

[USAFRet]

I was thinking outside the box saying, well connect 1 end of the 4-pin to one PSU in the computer, and setup the other PSU outside the computer with nothing running off of it except to connect the 2nd 4-pin connector to it.
Results = 1 PSU feeding the computer + Nvidia card and the 2nd PSU feeding only the Nvidia.

sniff sniff...I smell smoke.

 

[GregC1982]

Don't see a reason it would smoke! The connector made by Nvidia that came with the card is designed to connect to 2 different 12v rails and combine power into the 6-pin?

 

[bignastyid]

Don't see a reason it would smoke!

That's part of the problem.

Either wait for the PSU replacement or buy a new PSU. Also those molex to PCI-e adapters are fire hazards.

 

[GregC1982]

Ok now, I found some more threads about this. The only concern is when you try and power 1 device from 2 PSUs, and that is where the problems start or sometimes end lol smoky smoke smoke
And in a nutshell that's what my original post was doing....time to rethink.

So after reading the others threads there seems to be no reason I couldn't power the Nvidia from the 2nd PSU. And since the GTX 550TI requires a min 400w PSU (which is because the PSU has to power the entire computer and the Nvidia), normal stuff, the Nvidia in fact will never draw 400w from the PSU.
Therefore, the 2nd PSU should be able to power the Nvidia (by itself) as long as it's 12v+ rail can support the 24 amps max required by the Nvidia card.
In other words, connect the 2nd PSU ( using only 1 of the 4-pins and 6-pin connector) and power the GPU by itself. So now we have a dedicated PSU for the Nvidia all on it's own.

bignastyid: yea I prob won't do it because I can't afford to smoke my entiere desktop lol I was just curious if it's even possible.

 

[USAFRet]

No, the problem is...unless you get it exactly right, 1PC and 2 power supplies.
Not 2x PSU on the GPU...2 PSU in the PC as a whole.

Can it be done? Yeah, kinda sorta. But not with 2 substandard PSU's, and not without a lot of other research and investigation.
And by the time you've done enough research and investigation into how to do this...you're replacement will have arrived.

Don't do this.

 

[GregC1982]

I did some playing around and after a lot more reading on the subject. Since I have 2 extra psu's I wasn't worried about breaking one. Nor my computer either since it's pretty old and can only have a mac of 4fb ram lol.
PSU-1 max watts 300, max 12v amps 19
PSU-2 max watts 265, max 12v amps (don't rem and it's installed right now while STILL waiting on Corsair to acknowledge my email from Thursday night) ugh, they taking their sweet azz time.

So I tried the dual psu. Connected psu 1 to GPU only and jump started psu 1 green wire. The psu would power up, then after a few seconds it would turn off. Found out that unless I connected a hard drive to its Serial ATA connection it wouldn't stay on? This particular psu has the 5th orange wire on the Serial ATA plugs (and according to what I've found, that 5th wire 3.3v was never used on devices). What I couldn't find was whether or not it would hurt any of my devices since my other psu doesn't have the 5th wire. So I just snipped the orange wire.
So when I connected both the psu 1 worked "until" I loaded a game then the psu would shut off.

So then I removed all that, and tried connecting my GPU to the installed 265w max psu using the 4pin to 6 pin connector included with the Nvidia card. Remember, this is the psu currently installed.

Well get this.... it works perfectly fine, 12v stays around 11.85v, and could never see any amp draw off its 12v rail. I even ran wow for an hour, no issues, no high temps, frame rates around 107fps with game video settings to lower settings(which is where they've always been.

So now I have psu1 just powering the exhaust fan and I put another spare supply fan in the front if my case, and psu2 (installed) running computer and gpu.

Still not sure why psu1 was shutting off like it did? I had green wire from psu 2 running to green on psu1 and it would turn off and on with my computer power button.