DIY Make 2 SMPS(PSU) Work Together in a Single Pc...




Introduction: DIY Make 2 SMPS(PSU) Work Together in a Single Pc...

its not possible to write all that here..

Run your high end graphics card with a low end PSU costing as low as Rs 300 to 400...Cant believe??...Check this out guys....

Step 1: Tight on the Budget??? This....

This is my second instructable i am posting.All u gamers out there,this is a good hack that u can use.Graphics cards are the most power hungry component of a PC.Most graphics card nowadays comes with one or two 6 pin PCI-Express connectors to supply them power.This requires a powerful high end PSU.After investing Rs 10000 (convert to your respective currency if u are from outside India) on a good graphics card,it becomes a strain on the pocket to invest another Rs 5000 on a high end PSU that have the 6 pin PCI express connector.Well,If u have the affordability or u are worried about the impacts of a cheap PSU in the long run,u may ignore this thread.But i assure u,its more important to use a good UPS(which has a built in stabilizer) and have your house properly earthed.Without proper earthing, a high end PSU may fail within 6 months.

Step 2: What May Be the Solution???.... :-/

Actually i am in a bit of a situation here which u also may face someday....i am explaining it step by step..

1. I have a NVIDIA GTS 250 1GB DDR3 graphics card...but its only DirectX 10 enabled.

2.I bought it for Rs 10,500 along with a COOLER MASTER EXTREME POWER 600W PSU which costs Rs 4000.

3.Now, i need to sale my GTS 250 but i want to keep my PSU cuz its working fine and buying a new one will also cost money.

4.But the person buying it is buying an used card because he it tight on budget.

5.So the buyer wont be able to afford Rs 5000 on a new PSU who is buying an old card for Rs 3000.

6.So,the net result is...I will never be able to sell my Graphics Card....:-(

Then,an idea came to my mind....

Step 3: The Hack Begins....

The concept used here is to use two isolated power sources and to integrate them into one computer so that they will be switched on and off simultaneously,but will not share their power.It means the second psu is only meant to drive ta graphics card,but will start and stop with the primary PSU.

For doing this,I took 2 FRONTECH 400 Watt cheap power supplies each costing Rs 300.Take the two power supplies and carefully notice the 24 pin ATX power connector.

There is a GREEN coloured cable in the above pic and just adjacent to it is a black coloured cable.In normal situation,when the PSU is open(not connected to the motherboard or anything), it doesn't start just by hooking it up with the AC mains.U need to short circuit the green and the black cable with a pin or some small wire. So basically when u start a PC by switching on the Power button on the cabinet,u are just shorting these two wires.

Step 4: Do It Carefully....

Cut away the GREEN and the adjacent black wire from the secondary PSU keeping a little wire from the base of the connector as shown in the above picture.(If u want to use it as a standalone PSU in future)This wire will definitely be short.So u may add some wire to extend it as u may have to place this PSU outside the CPU cabinet,but do insulate the joints.Then cut away the green and the black wires from the main psu in the same way,strip away a little length of the insulation each from the 4 pieces of wires u obtain after cutting.Take the two wires from the second psu and join the green and the black wires to their respective coloured wire of the main psu, and then twist them around the wire that is coming from the connector correspondingly.Insulate all the bare ends and you are done.

Step 5: Lastly U Need to Buy This Connector...

This is a 6 pin PCI Express connector that u can buy from for Rs 100.

Below is the link..

Buy it and you will be able to able to run High end games with a low end PSU.

U will have two SMPS working together.Hook up your PC and Graphics card properly...and enjoy.....:-D

Of course, Reliability is a question here....but for rocks...:D...

Disclaimer: I am not responsible if you burn your graphics card or motherboard or anything else doing this...Best of luck....



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    15 Discussions

    when CPU jam and automatically restart, the secondary PSU not start, what issue of it? i need to shut down and restart again then the secondary psu only can start

    im going to try this tonight!

    I love when the urge for understanding makes people actually try things out and at the same time puts prestige aside. Prestige in argumentation that is a part of the old world where scientists were battling each other, keeping results secret until critical moments. If something breaks along the way when I try things its just a part of the process.

    You still have a voltage differential and potential short circuit between the two PSUs, the graphics card is slotted into the mainboard. Potential exists between the + power on both devices(since they are separated). It may not happen today, tomorrow, or the next day, but when you get unreliable power(say no Uninteruptible Power SUpply, due to costs) or a load on one and not the other, you will have problems. Before wiring something like this up you should take some lessons online about basic electrical wiring, as micro-electronics are actually "advanced".

    Interesting write up but power supply units like those are not meant to be parralled. It's a special type that allows parralled operation and those usually have a master slave(s) arrangements via a communications channel. This is the reason that brand name (or even diy) desktop pc machines never have multiple psus.

    Your arrangement (even on the merit of low cost) will cause rapid failure of the motherboard and or psus. The reason being is when you tell Windows to shutdown and the hardwired psu stays on. What do you think will happen? Also the small tolerances in voltage difference across each psu.. They cannot handle backfeed.

    3 replies

    the only thing the two psu's shared was a common ground and the pson wire they weren't wired in parallel so voltage differences doesn't matter one was used to power a graphics card and the other was used to power everything else

    I have to disagree. If you were using the second supply for fans or led mods only there is no problem. GPU on the other hand gets power from PCI-E too exept the 6pin connector so there is a change to fry your mobo or GPU or both with the small tolerances in voltage difference across each PSU.

    There are connectors that can power up the second PSU (for fans, leds, pumps only) easily with just a relay. If you have a spare bad mobo to get the psu connector, a 12v or 5v relay, a female molex and a resistor u can build it and have "safer" results. I will not provide link but only the name of this adapter: Add2Psu Adapter


    a better way to get it to power on would be to run a longer wire between the green wires on both power supplies that way they both turn on together eleminating the spike that comes from powering the second one manually

    do not use molex to PCIe power adaptors for hugh end GFX cards! (high end means any card that needs more than one PCIe power adaptor) and god forbid using two separate PSUs to power one GFX cars. You mentioned in comments that you are using one gfx card for graphics and other for everything else, which may work for a while but note that new 750W psu costs less than 100$ . Just as EvolvedAwesome said, one PSU is always better than two (in case of consumer PC)

    Just to anyone who is going to attempt this, it is always better to opt for 1 PSU over two!

    My computer has two PSUs. One is the same AX1200i that you appear to have. The other one is a Thermaltake Power Express 650W. It is only used to power the graphics card. It basically hookes up just like you did it. It was designed by Thermaltake for that purpose explicitly and it appears to work well in my computer for the last couple of years. It has a ground reference wire and a green power on wire and both PSUs turn on and off together. It is a bit unusual but my graphic card (Asus EAH5970) draws 22 Amps by itself. My previous main PSU was not able to provide that much current on a single rail. The Thermaltake solution solved my problem and continues to work well. Nice effort on yor part to explain what you did.