How to use 2 PSU's on one pc

TheModDoctor · Post by **TheModDoctor** » 17 Jan 2008, 19:21

Recently I've been looking to upgrade my graphics card, but I had insufficient power. So I thought why not just add an extra 200watt PSU that was laying around instead of spending heaps of cash on a new one. My goal with this is that I can connect all my HDD's, CD-ROM's, fans and lights onto the 2nd 200w PSU, and only the motherboard and graphics card on my main 400w PSU. So now I'll be showing you how to use 2 power supplies on one computer

This is my how my case looks

And this is the 2nd 200w PSU that I will add

Disconnect everything, and I recommend that you take out your HDD as well.

Cut the green wire on the 2nd PSU. Don't worry, you don't have to guess James Bond style, because there is only one green wire

Also cut the black wire that is between the green and the blue wire.

Cut the same 2 wires on your main PSU

I will use this wire to link the 2 psu's together. How this works is if you hit the power button the motherboard connects the green wire to the black wire to turn on the PSU. Thus if the mobo turns on the first, the second one will also turn one. I marked two of the connected ends so I will not get confused. I call this the "link wire"

This is how I will connect the link wire to the main PSU

But before I do that, I will first connect the link wire to the 2nd PSU. (You see that the black marked ends will be connected to the black wire...)

And now to mod my main PSU as well... I don't really like the idea of having 2 power cables come out of my computer, so I will give the 2nd PSU power directly from the main PSU. Be very careful when opening a PSU, because the capacitors might still contain some charge. Wait a few minutes after you unplugged the psu, or wear some thick rubber gloves. Always better safe than sorry.

I will use this standard power cable,

and cut it in half.

Keep the part that you plug into the PSU, and strip the wires.

Now solder them on where the main PSU's plug is located. Now this will feed the main PSU and the 2nd one. Brown on the left side and Blue on the right. Sorry for the low res pic.

Now reroute the cable out with the others and close your main PSU.

This is where I will fit my 2nd PSU for the time being.

Now connect the link wire. DO NOT SCREW IT UP.

You can make extra sure that the green wire will be connected the the green wire, and the black to the black wire...

Plug in the cable from the main PSU into your 2nd PSU.

Put back the HDD,

and plug everything back where it belong.

(Logically you will use your 2nd PSU plugs as well...)

Put the case back on the table and plug everything in

Push the power button...

And VIOLA!

I enjoyed doing this mod, and I hope that if you find it usefull, it will serve you well... Oh and remember, on your own risk.

Regards,
TheModDoctor

DarkRanger · Post by **DarkRanger** » 17 Jan 2008, 19:40

cool guide.

Mauritzvw1 · Post by **Mauritzvw1** » 17 Jan 2008, 20:21

Kwl man!

a suggestion if I may...

mount the 2nd psu at the top of ur case either in the 5.25 bays or just behind and vent the extractor fan out the top with a duct or out the side panel. Where it is at the moment ur gonna put a lot of heat in ur case

Nice idea tho , I might follow suit

ps. I just noticed you have an unused 80mm fan mount at the back, maybe try duct it out there, but dnt disrupt airflow to the cpu fan

StarBound · Post by **StarBound** » 17 Jan 2008, 20:32

Now if only you can fix Eskom there wont be problems

TheModDoctor · Post by **TheModDoctor** » 17 Jan 2008, 20:39

Mauritzvw1 wrote:Kwl man! a suggestion if I may... mount the 2nd psu at the top of ur case either in the 5.25 bays or just behind and vent the extractor fan out the top with a duct or out the side panel. Where it is at the moment ur gonna put a lot of heat in ur case

Nice idea tho , I might follow suit

ps. I just noticed you have an unused 80mm fan mount at the back, maybe try duct it out there, but dnt disrupt airflow to the cpu fan

thanx dude

. Yeah I know I'm putting lots more unwanted heat straight into my case, so I'll really look for a better place to mount. Maybe like you said, through the open fan slot...

StarBound wrote:Now if only you can fix Eskom there wont be problems

BWAHAHA

Yeah thats the plain truth

elviz · Post by **elviz** » 21 Jan 2008, 09:37

this....is eggzactly wot i needed....cant wait to get home .....thx dude.

Ark · Post by **Ark** » 21 Jan 2008, 11:19

Thanks man!

I really needed a guide like this!

Arillis · Post by **Arillis** » 11 Feb 2008, 10:46

Thanks.....sorted!

Vampyre_2099 · Post by **Vampyre_2099** » 11 Feb 2008, 11:12

Really nice mod, very useful too. Thanks

Hex_Rated · Post by **Hex_Rated** » 11 Feb 2008, 11:52

Nice guide! Careful when you open PSUs. The capacitors can still retain charge and you can get shocked. Wear thick rubber soled shoes in case. The chance is quite minimal but rather safe than sorry.

Samaya · Post by **Samaya** » 11 Feb 2008, 12:52

I am glad you are trying to balance the power used by the 2 supply's. If you didn't you might have gotten a voltage difference between the two sets of black wires (The negatives). I would still suggest you connect the two sets of black wires more securely together (a nice thick wire between 200W and 400W negative lines). That way you can eliminate any voltage differences between your MoBo and say HDD for instance increasing the life expectancy of both...

RobThePyro · Post by **RobThePyro** » 11 Feb 2008, 17:31

Samaya wrote:I am glad you are trying to balance the power used by the 2 supply's. If you didn't you might have gotten a voltage difference between the two sets of black wires (The negatives). I would still suggest you connect the two sets of black wires more securely together (a nice thick wire between 200W and 400W negative lines). That way you can eliminate any voltage differences between your MoBo and say HDD for instance increasing the life expectancy of both...

QFT

TheModDoctor · Post by **TheModDoctor** » 11 Feb 2008, 17:59

Thanks! I'm glad you guys liked the guide.

Samaya wrote:I am glad you are trying to balance the power used by the 2 supply's. If you didn't you might have gotten a voltage difference between the two sets of black wires (The negatives). I would still suggest you connect the two sets of black wires more securely together (a nice thick wire between 200W and 400W negative lines). That way you can eliminate any voltage differences between your MoBo and say HDD for instance increasing the life expectancy of both...

Thanks, I will do that. What I did was connect the hdd, cd-rom, lights and fans to the 200w psu, so that my 400w can drive my mobo and new graphics card. I wanted to get the load off my 400w because I was unsure if it would have been enough, but now I've got no problem.

Hex Rated wrote:Nice guide! Careful when you open PSUs. The capacitors can still retain charge and you can get shocked. Wear thick rubber soled shoes in case. The chance is quite minimal but rather safe than sorry.

Truth to that. I'll edit the guide, because this is quite important. Thanks.

RobThePyro · Post by **RobThePyro** » 11 Feb 2008, 19:41

TheModDoctor wrote:
Hex Rated wrote:Nice guide! Careful when you open PSUs. The capacitors can still retain charge and you can get shocked. Wear thick rubber soled shoes in case. The chance is quite minimal but rather safe than sorry.
Truth to that. I'll edit the guide, because this is quite important. Thanks.

IMHO "thick rubber soled shoes in case" not gonna help you much(unless your barefoot on a very good ground like a metal floor...) and since a capacitor has both + AND - so if you were to touch the wrong pins and they were charge it would discharge through you regardless of your shoes... (LOL) so the SAFEST way is to get a (plastic handled) screwdriver or something and short out the pins of the big capacitors (ignor the small ones) and you will be good!