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OCZ Modxstream-Pro 700W connection with SLI GTX 560 cards

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May 4, 2012 10:50:03 PM

Hi, I bought 2 Asus GTX 560 cards and I want to connect them to my OCZ 700W Pro. The first plugs into the two PCI-E ports on the PSU, but I have no idea how to power the second. I have two six-pin power ports on the 560 that need to be supplied, and I have two spare six-pin ports on my PSU.

What cables do I need to use to connect my second GTX 560 to my PSU?

Many thanks in advance!
a b ) Power supply
May 4, 2012 11:27:23 PM

Your missing the cables to connect that? It should have included them with the PSU.
May 4, 2012 11:31:06 PM

No, as you can see in the link, there are only so many cables provided, thus I am not missing a cable, per se, just never had enough in the first place. I would love to know which cable I need and if it will work! Thanks :) 
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a c 87 ) Power supply
May 4, 2012 11:32:22 PM

The 6pin ports on the PSU are supposed to be used by peripheral and SATA cables.

The only way to do it is to use 4pin peripheral (molex) to PCIe adapters, which often come with graphics cards.
There is a possibility that you will overload the +12V2 rail on a very heavy graphics load as both GPUs and all HDDs have to share 25A. Some of the graphics power will be delivered through the motherboard which draws from +12V1, so that is the saving grace in normal loads.
May 4, 2012 11:36:23 PM

Thank you for this reply, it's what I've heard elsewhere. I know this is going to sound really dumb, as you guys know this stuff inside out, but how do I do the molex connection? I have several six pin male to two 4 pin molex male adaptor (these: http://www.gttkc.com/shop/images/molex_pci-e.jpg ), but what do I do with them? Does the 6 pin go into the GFX card? In which case, how do the molex ends get connected to the 6 pin port on the PSU? Thanks.

(A side note: will the use of a SSD, as I have in my computer, reduce the draw under heavy load?)
a c 87 ) Power supply
May 4, 2012 11:58:49 PM

From that picture; the black end, with 6pins goes into the GPU. The white end goes onto the 4pin molex that comes from the PSU.

Compared to an ordinary HDD, yes an SSD will reduce the power draw.
May 5, 2012 12:03:09 AM

I just took a look in the case and there's no 4 pin molex from the PSU. Am I missing something here? Do I need another cable from the PSU?
a c 87 ) Power supply
May 5, 2012 12:06:07 AM

The 4pin molex connectors are modular on the OCZ MXSP 700W, so they aren't automatically connected.
There should be four of them on two cables, in the case of the MXSP 700W they are black as seen here:
http://power.zol.com.cn/118/1183116.html
(bottom picture)
May 5, 2012 12:18:53 AM

Thank you so much for finding that! I get it now! I seem to have misplaced this cable right now, but I'll endeavour to find it. If I don't, what is it called so I can find it online/is there a store link for it? And also, surely I need 4 molex slots (2 for each 6 pin slot on the GFX card), and that cable only provides molex outputs. Do I just connect one molex to each 6 pin on the GFX card?

Once again, thank you so much for your patience and great replies!
a c 87 ) Power supply
May 5, 2012 10:21:09 AM

You'd be better off asking OCZ if they'll send you replacement molex cables. This is because cables are rarely interchangeable between different units and I'm not convinced those cables get sold separately.

They are commonly referred to as any combination of 4pin peripheral molex.

Yes you will have to use all four molex connectors to provide the two extra 6pin PCIe connectors that a GTX 560 needs.
If possible the two GTX 560s should share the 'native' 6pin PCIe connectors, so they each get one each and then share the PCIe connectors that are adapted from the molexes as well.
a c 243 ) Power supply
May 5, 2012 3:28:30 PM

Don't know how comfortable I'd feel running a pair of 560's on that psu, but,

One option is pcie power splitters
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Quite a few psu's make use of dual pcie connector cable's



4x GTX580's using dual connector cables, can be seen 5 seconds in
http://www.youtube.com/watch?v=7V13ZGIZgYY

Also;
The connector pinout is labeled on the MXSP,


If you're comfortable repinning connectors any 4 or 5 wire/6 pin modular peripheral cable can be repinned to work on it
Google ; ATX pin removal

I'd go with option 1, less cable clutter
!