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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

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.

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.

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/

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

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

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.

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

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

Is it only needed on some PSU or ?

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 ?

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)

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.

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.

http://www.cablesaurus.com/ :D

but the price is kind of high...

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

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 ;)

ok 2nd psu worked just fine with gigabyte 5850 and 5770, but when i placed 5830 instead of 5850, 5830 xfx died..

theres no chance there was not enough power, so wtf happened,now when i put it in x16 system deasnt load at all, just vents working, and when i put it in x8 system works fine but theres no picture at all.

any ideas?   sure hope i get replacement for that 5830

Ive had 2x 5850's that failed on me. Very strange problems like yours, Just wouldnt recognise them 2 cards in any mining tools or OC program with any configuration. Them 2 cards causes alot of fiddling about cause i didnt relise there was 2 faulty ones. Weird thing is they booted fine on there own but failed to initialise mining. Overclockers in the UK did actually replace them with that fault and confirmed it, which quite suprised me as the cards themselves worked fine with games or any other 'everyday' task :) Check the AMP's your card is using and see if the PSU links up. 1 run 4x5850's all OC's pulling 100-120AMPS and my PSU's are 1200W @98Amps (ANTEC HCP1200) so it as a little overhead on the wattage and a little under on amps. Thats can damage hardware but theres not alot i can do about that. Dins a PSU that dishes out more than 100AMP, DOnt exist :( Corsair AX1200 is the better supply by the tinyiest of margins though.

moral..... DONT BUY CHEAP PSU's, DO YOUR RESEARCH ON THEM, CORSAIR AX models, ALL OF THEM are the best CURRENT PSU's out there, imho and many others ;)

Me think you just made the price rise by another 5%

Truth is that there are many good PSU and unless you've read a 12 page review of one you don't know what you're buying.

I have good feeling about OCZ Z series 1kw gold , + cheap

ok, so my 5830 didnt die after all.
it seams that my mbo ( http://www.gigabyte.com/products/product-page.aspx?pid=3901#ov (http://www.gigabyte.com/products/product-page.aspx?pid=3901#ov) )  doesnt support 3 gpus... but i dont get why it has 3 pciex slots ...

i feel realy dumb now..

anyways i setted up 2x psu system with dummy load on 2nd one of 6x 75ohm resistors connected serial to get 450 ohm on 3,3v rail @ 0,024w . on 5V i placed a small fan @ 0,6 w. that works perfectly.

3rd gpu i removed and will put in 2nd rig aparently, still cant believe about the mbo...   ???

Where does it say it doesn't support 3 gpus?

don't feel dumb, If I couldn't use 5 gpu on this board I'd ask for a refund.

Is 0.02 watt really making a difference ?

I tried and it didnt work, later i found in manual and on official page that it supports upto 2 crossfire..



Y, 0,02w makes a difference coz w/o that load it wont jump start ..

I have yet to see a board on which you can't use all PCI-e 1X for mining, even old board with pci-e 1.0

What is this 16x for if not for GPUs ?

You shouldn't be using crossfire for mining anyway. The cards should just be running standalone. Crossfire doesn't help and I've read some reports here it reduces hash rate - though I've never tried it to see.

In the specs it says that the two x16 will use x8 mode if both are installed but that shouldn't prevent them from working for mining and the x1 should still work.

It supports up to 2 GPUs in crossfire. But mining does NOT require crossfire, thus the limit is not an issue for you.

I got a gigabyte that wont accept more than 3. Gigabyte are a load of rubbish. I found perfectly good MSI boards with 'military' grade for £45 and they dont wimper. All my gigabytes are iffy in some way or another. AVOID is my advice. MSI seem to be best boards but thats not suprising. Maybe not as good as they used be but towards gigabyte its like comparing a coke to a 11p asda(wallmart) special

Well I have a gigabyte mobo with two 16x slots and two 1x slots.
Will test if it takes 4 gpus.

Ive owned 3. 1 blew when i plugged the 5th card in with no powered extenders (more than 300W draw from the mobo killed it), 1 in a PC with i5 setup and good memory (3x 5870's) which wont accept the 4th, and another on one of my 4x5850 rigs, which is the one thats not being 100% server style :( Does have ubuntu multi boot so goona clean and start again on it. Sticking with windows, Get better everything in it. Never thought id be saying that, EVER :)

Also have a Gigabyte motherboard. It's being advertised for quad SLI etc, however, it won't accept 4 GPU's...  I've opened a support case with them...

Good luck.... :)

MSI boards are the best, SO reliable and not crammed full of bloatware etc. Simple board and electronics, Just like the old DFI boards, R.I.P (although the comp im on now is a DFI NF4 Delux still rocking it 9-10 years down the line :)) Doesnt like a 5850 shuved in it though :( Gets artifacts and all sorts. Noticed it has a molex power connector on the board so it was the transition to the 4 pin 12V connector (now 8 in some).

I know that I am real late to this thread but check out this site.
 www.add2Psu.com