Multiple power supplies.

[ajareselde]

Here is the deal;
i need to hook 2 power supplies to my rig.

how can i set it up to both start at the same time? is it safe to use 1 psu on mbo and 2 gpu-s, and 2nd one on other 2 gpus ?

would be nice if u could point me to some associated thread.

cheers

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[k9quaint]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

[BkkCoins]

A dual-adapter works but you can also hook it up yourself and get the same results if you can't wait for one to come in the mail.

On the ATX connector you join the green wires from each PSU and one black wire from each.

PSU1   PSU2
blk ---- blk   (Ground)
grn ---- grn   (PWR-ON)

When the power on (green) line on the first PSU gets pulled low it now also pulls low on the second - which causes both to turn on. There is only a very small signal current on this line.

To do this some people just push a wire into the pin slot to make contact. Ideally you would solder it but also pulling the pin and wrapping around it works. There is usually small "barbs" inside on the pin and they need to be pressed in to release a pin. I've also seen pics of people who used "splice" connectors but I'd personally prefer not to damage the wires on the PSUs.

[m3sSh3aD]

Here is the deal;
i need to hook 2 power supplies to my rig.

how can i set it up to both start at the same time? is it safe to use 1 psu on mbo and 2 gpu-s, and 2nd one on other 2 gpus ?

would be nice if u could point me to some associated thread.

cheers

Green and black cable on the 24 pin, 3-4 along top row from left. Link them together and it comes on

It works....

http://imageshack.us/photo/my-images/694/imag00032w.jpg/

[haploid23]

i'm also using dual PSU on one of my rigs. does it matter that they do not have a common ground?

[m3sSh3aD]

I wouldnt think so, but that depends on where you are and many other factors. Im UK so solid 230-240V

[BkkCoins]

i'm also using dual PSU on one of my rigs. does it matter that they do not have a common ground?

As soon as you connect them to the cards they have a common ground anyway. I'm not sure if there's a valid reason to explicitly add a ground on the connector but it can't hurt either, and is the way people have been doing it.

[chungenhung]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

[Transisto]

What about the need for pulling from 3-5v ?

Is it only needed on some PSU or ?

[ajareselde]

Update:

i finaly bought everything i need, but 2nd psu wont jump start without load.

i tryed hooking 2x 2.5 inch hdds, and some vents, but still nothing.

tryed also with 75 ohm resistors on 3.3v line and again nothing....   ideas ?

[Transisto]

I'm personally having a few built setup this way.

I just strip the two (green and a ground) twist them, then the PSU stay ON all the time,

I power the "stay on" before the other on the mobo.

work well. (so far)

[BkkCoins]

Some PSU need load on 5V and some don't - according to what I've read. Apparently if the PSU is "group regulated" then it needs that load. I've also read that 100mA should be enough but haven't tested that myself. I don't know if 3.3V line is just as good  but I suspect it is derived from 5V and would be the same.

V=IR, R=V/I R = 5 / .1 = 50 ohms

So if you have 75 ohms you may need two in parallel, = 37 ohms.

@ 37 ohms, I = V / R = 5 / 37 = 0.135 A
P=VI = 5 * 0.135 = 0.675 W across two resistors is 0.38 W each.
So you would want 1/2 W resistors for that.

If you only have 1/4 W resistors handy you should likely use a higher 100 ohm value or they may burn out after a while. Or put more in parallel or try on 3.3V line.

If you put 2 parallel 75 ohm on the 3.3V line you'd have 89mA - maybe enough.
And power dissipated in resistors would be 3.3 * .089 = 0.29W total or 0.145 W each.
Probably ok.

3 75 ohm inparallel on 3.3V line is 132 mA. And 0.436 W / 3 = 0.145 W each as well.
But this gives a bit more load.

[ajareselde]

Some PSU need load on 5V and some don't - according to what I've read. Apparently if the PSU is "group regulated" then it needs that load. I've also read that 100mA should be enough but haven't tested that myself. I don't know if 3.3V line is just as good  but I suspect it is derived from 5V and would be the same.

V=IR, R=V/I R = 5 / .1 = 50 ohms

So if you have 75 ohms you may need two in parallel, = 37 ohms.

@ 37 ohms, I = V / R = 5 / 37 = 0.135 A
P=VI = 5 * 0.135 = 0.675 W across two resistors is 0.38 W each.
So you would want 1/2 W resistors for that.

If you only have 1/4 W resistors handy you should likely use a higher 100 ohm value or they may burn out after a while. Or put more in parallel or try on 3.3V line.

If you put 2 parallel 75 ohm on the 3.3V line you'd have 89mA - maybe enough.
And power dissipated in resistors would be 3.3 * .089 = 0.29W total or 0.145 W each.
Probably ok.

3 75 ohm inparallel on 3.3V line is 132 mA. And 0.436 W / 3 = 0.145 W each as well.
But this gives a bit more load.

ill try this after work.

+12v rails will be loaded with gpus.

+5v with hard drives

+3,3v with resistors

ill post how it went later.

[BkkCoins]

Also just try that 2nd PSU on it's own with hard drives/loads. Or swap it with #1 and make sure that the PSU doesn't have some problem that no amount of tweaking will fix. Or try it in another system.

[c_k]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

http://www.cablesaurus.com/

[chungenhung]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

http://www.cablesaurus.com/

but the price is kind of high...

[ajareselde]

Also just try that 2nd PSU on it's own with hard drives/loads. Or swap it with #1 and make sure that the PSU doesn't have some problem that no amount of tweaking will fix. Or try it in another system.

2nd psu is fine , under load it boots up perfectly.

[m3sSh3aD]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

http://www.cablesaurus.com/

but the price is kind of high...

Ebay, £3.36 for x1 to x16 extender. Cant find power molex on ones for less than 8-10 quid though. Cablesauraus is having a laugh. Making pure $$$$$$$ So easy do and no ones doing it no where. Go east, all im going say

[chungenhung]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

http://www.cablesaurus.com/

but the price is kind of high...

Ebay, £3.36 for x1 to x16 extender. Cant find power molex on ones for less than 8-10 quid though. Cablesauraus is having a laugh. Making pure $$$$$$$ So easy do and no ones doing it no where. Go east, all im going say

This thread is about chaining two PSUs. NOT about PCIE exenders

[m3sSh3aD]

Get one of these so the power switch will turn on both power supplies.
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=34_186&products_id=21193

Then just split the PCIE plugs to the vid cards between the PSUs.

They are out of stock, so is FrozenCPU.com.
Anyone know where else to get them?

http://www.cablesaurus.com/

but the price is kind of high...

Ebay, £3.36 for x1 to x16 extender. Cant find power molex on ones for less than 8-10 quid though. Cablesauraus is having a laugh. Making pure $$$$$$$ So easy do and no ones doing it no where. Go east, all im going say

This thread is about chaining two PSUs. NOT about PCIE exenders

Doh, got confused haha Still, cheap as on ebay. I use 1200W on 4 5850's, Reccomend corsair