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Modding two PSU


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dint google it just asking if like i could combine two PSU, i have one Antec 750W true power and a gtx 570 runs on it with couple of fans and probably a CPU cooler.

but in future suppose i wanted to SLI one more 570, the 750W can barely withstand the load,

instead of selling my current PSU and purchasing 1200W

so my plan is like this,

 

the 750W runs inside the cabinet and supplies power to all the system, and some basic 450W PSU will sit on top of my cabinet and connects ONLY to the other gtx 570 i hope 400W alone

is sufficient for that GPU and the PSU can be linked with my present power button to switch it on when ever the pc starts.

 

any one tried this before.. is it efficient and possible..??

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It is possible and I have seen it done. But it makes your system more unstable and even more complex. I think you should really get a 1200 watt PSU.

 

what are the complications..?

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You've got an ugly PSU just sitting on top of your case with wires going who knows where, using two power cables. It's a "basic" 400W, of questionable quality. If you sold your 750W, and didn't buy the 400W, you could probably just get a better PSU for a small price. Are you really going to trust your $300 video card to some $40 PSU? Not to mention the rest of your system, which it's technically connected to. It blows, it can blow everything else, even if it just powers the video card. It sounds like such a crappy situation to me, and if you can afford another 570 you can afford another PSU.

Edited by Darth_Tom

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It is possible and I have seen it done. But it makes your system more unstable and even more complex. I think you should really get a 1200 watt PSU.

stupid.gifYeah just the 1200w PSU, but I think thats a bit overkill maybe 1000w or a quality 850w would do.

 

You'll just have to short two pins, and you'll be able to use both power supplies

 

I wouldn't do this, because the chance of damaging your components is so high.

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Here is an alternative. I have two of these in my system in addition to my Corsair HX650w. They are very efficient, ultra low ripple clean power, and run very cool. (it's rated @ 85% efficiency, but goes higher than that))

It fits in an 5.25 bay and does not require spindling. It gets a bios wake up from a 4 pin molex. I use two of them to run my OC'ed 4 xHD 5850's.

Highly recommend them.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16817104054&Tpk=fsp%20group%20boosterx5

Edited by red1776

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I'm not convinced running two power supplies in this manner is a good idea but it appears to work very successfully over and over again?

 

Not all power supplies are the same. When the PC is switched it will only be allowed to post when the motherboard sees the PG (Power Good, PWR OK) signal from the power supply. The time for this power good signal is typically 100mS on good quality power supplies and as much as 500mS on low end generics. This means the motherboard could boot up with a PG signal from the main power supply when the auxiliary power supply isn't ready. Granted it's not a great deal of time but could this cause instability? I don't think you'd get away with one power supply for the 20/24 pin connector and another for the ATX12V/EPS12V connector (unless there was something synchronising both power supply PG signals) but using a seperate power supply for the graphics card(s) appears to work.

 

It's not something I'd personally do so I'd say always choose the right tools for the job.

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I'm not convinced running two power supplies in this manner is a good idea but it appears to work very successfully over and over again?

 

Not all power supplies are the same. When the PC is switched it will only be allowed to post when the motherboard sees the PG (Power Good, PWR OK) signal from the power supply. The time for this power good signal is typically 100mS on good quality power supplies and as much as 500mS on low end generics. This means the motherboard could boot up with a PG signal from the main power supply when the auxiliary power supply isn't ready. Granted it's not a great deal of time but could this cause instability? I don't think you'd get away with one power supply for the 20/24 pin connector and another for the ATX12V/EPS12V connector (unless there was something synchronising both power supply PG signals) but using a seperate power supply for the graphics card(s) appears to work.

 

It's not something I'd personally do so I'd say always choose the right tools for the job.

 

It has worked flawlessly for me (the FSP Group X5) option for 4 quad crossfire machines now. I have actually opted for this arrangement over a single huge PSU for 4 builds now. The quality of the power has been the issue for me, and running quad CFX has been a good test.

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At one point I had an Ultra 650W and an Ultra 750W PSU both hooked up to my system. (Powering dual 4890's)

 

It's not all that complex, but I wouldn't do it with a 400W PSU at any rate.

 

You just have to mod the PSU so that it's always on. To do this, connect the green and black wires on the mobo power connector. This can be achieved with a paperclip, or with a bit of extra wire. I suggest taping it with some electric tape too, to prevent shorts etc. Once it's modded, you'll use the power switch on the PSU to turn it on or off. (if it doesn't have a power switch, I suggest you don't use it.) ;)

 

Some cases are designed to hold two PSU's from the start (IE: HAF 932) and this little hack can save you 20 bucks or so, since you won't need a dummy plug.

Edited by Locutus

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