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Powering graphs card over 75W without 6-pin or 4-pin on Motherboard

Last response: in Graphics & Displays
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November 30, 2011 5:16:17 PM

Hello,

Is there any way to power a PCIe graphics card over 75W with a 6-pin connection on a motherboard without a 6-pin connection and no available 4-pin connections?

a c 153 U Graphics card
November 30, 2011 5:20:19 PM

Not really too sure what you are asking. If you have a GPU that requires a 6-pin connector you need to get a 6-pin into it. You can do that with adapters.

If you have NO available 4-pin connectors? (I assume you mean Molex?), then I think you might want to look into a GPU upgrade. You can get cheap good ones for around the 20 dollar mark.
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November 30, 2011 5:23:32 PM

Yeah so no molex or 6-pin connectors on the motherboard.

graphics card has a 6-pin connector.

What kind of adapter, only thing I've been able to find are for molex connectors to 6-pin.
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a c 153 U Graphics card
November 30, 2011 5:24:41 PM

On the motherboard? Do you mean on the PSU?

Molex to 6-pin is the adapter you need, if you dont have any molex connections available then you need a new PSU.
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November 30, 2011 5:28:07 PM

K, maybe I'm not being clear enough, no molex connectors on motherboard or power supply. Replacement of PSU not possible.

Only available sources of power include USB port and additional PCIe slots.
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a b U Graphics card
a b V Motherboard
November 30, 2011 5:28:44 PM

You are talking about the 4 or 8 pin connector on the motherboard that will help it power video cards. I am not sure if there is a converter cable from a 6 pin to a 4 pin to do what you are talking about.
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a c 153 U Graphics card
November 30, 2011 5:28:56 PM

Hate to break it to you, but you're screwed if you can't replace the PSU. That is your only option. Either that or unplug something connected to molex that is uneeded, maybe an additional ODD, or a fan.
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November 30, 2011 5:31:30 PM

Thats sort of what I thought, wasn't sure if someone made a USB to 6-pin adapter or a PCIe slot to 6-pin adapter/passthru.
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a c 153 U Graphics card
November 30, 2011 5:33:28 PM

I've never heard of or seen them if they are out there, so I doubt it. I find it very hard to believe you dont have an available molex anywhere.
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a c 130 U Graphics card
a b V Motherboard
November 30, 2011 5:36:25 PM

No you can get Molex pass troughs but I really wouldn't recommend doing that to power a GPU.

What I now have to admit wondering is what sort of PC are you running. It must be very low end to not have a PSU with no PCIE cables and no spare Molex connectors ? If this supposition is not misplaced then I doubt the rest of the system could keep up with a card needing extra power anyway.

Mactronix :) 
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a b U Graphics card
a b V Motherboard
November 30, 2011 5:41:09 PM

USB provides only a few watts of power so you really shouldn't try to power anything with it unless it was designed to be powered by USB.

You can get a Molex splitter (a Y cable) and then a molex to 6-pin PCIe, but I wouldn't recommend it unless you want to do the work and figure out how much power is being put through the wire that connects the Molex plug to the PSU (since there are typically multiple molex connectors all attached to the same wire going to the PSU). If you draw too much power over an 18 gauge (I believe that is the correct gauge) wire you are risking a fire.

If you had a free cable with molex connectors not doing anything then I'd say a molex to 6-pin pcie would be fine.
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a c 153 U Graphics card
November 30, 2011 5:42:28 PM

Doh! Totally forgot about a molex splitter.

Regardless of that I wouldn't attempt it myself.
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November 30, 2011 5:43:49 PM

Sorry, thanks for the help, but I'm guessing I'm not making it clear, no molex connectors at all, none in use, etc, please look at link above for system information.
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a b U Graphics card
a b V Motherboard
November 30, 2011 6:05:24 PM

elrondvega said:
Sorry, thanks for the help, but I'm guessing I'm not making it clear, no molex connectors at all, none in use, etc, please look at link above for system information.


I didn't see the link. With a quick search I couldn't find out what kind of connectors that PSU comes with.

Either way, you can split 12V and ground off of any internal wiring with a bit of work and tie it into a 6-pin PCIe connector. I once split off 12V to automatically turn on & off a cable modem whenever my server rebooted.

Also, why are you trying to put a power hungry graphics card in a server?
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November 30, 2011 6:05:27 PM

Am I missing something here? Out of connectors, so replace the PSU?

I found two Molex splitters within arms reach of my desk, and I have a whole drawer full of them across the room. They're cheap and not hard to find. I imagine it would be a heck of a lot cheaper and easier to try one of those rather than to replace the whole PSU just to get another connector.


EDIT: Wow, I gotta spent less time proof-reading. Somebody got it saying it before me while I was spell-checking . . .

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November 30, 2011 6:25:19 PM

nordlead said:
I didn't see the link. With a quick search I couldn't find out what kind of connectors that PSU comes with.

Either way, you can split 12V and ground off of any internal wiring with a bit of work and tie it into a 6-pin PCIe connector. I once split off 12V to automatically turn on & off a cable modem whenever my server rebooted.

Also, why are you trying to put a power hungry graphics card in a server?


The power supply doesn't have any connectors directly attached to it, it connects directly to the motherboard only.

I was hoping for a solution that wouldn't have me cutting and splicing cables together.

I was really hoping for a simple PCIe card with just a 6-pin power output on it to put in one of the other slots
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a b U Graphics card
a b V Motherboard
November 30, 2011 6:34:11 PM

elrondvega said:
The power supply doesn't have any connectors directly attached to it, it connects directly to the motherboard only.

I was hoping for a solution that wouldn't have me cutting and splicing cables together.

I was really hoping for a simple PCIe card with just a 6-pin power output on it to put in one of the other slots


that is what I was guessing, but wasn't sure. Yea, I don't know of any solutions for what you want to do. The other option is step down to a GPU that only draws 75W from the PCIe slot.
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November 30, 2011 6:45:40 PM

Thats what I'm currently running(Radeon HD 5670), I was hoping to come up with a more powerful solution. I'm guessing I can't do SLI or crossfire, since I don't think the motherboard chipset supports either of them.
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December 3, 2011 9:31:51 AM

My Dell PowerEdge 2850 is similar and I wanted to install an HD 5770. In the PE 2850 the dual power supplies are hot swappable.

What I had to do is bust out my volt meter and perform a little surgery. The hot swap power supply had some even number of power takeoffs. With some testing it turned out that I had +12v rails and ground rails. No +5v rails, but that's OK since the 8-pin adapters want +12v.

What I did then was map out the electrical connections required for the 8-pin adapter, and soldered the appropriate wires to either the +12v or ground. It actually wasn't that difficult once I got over the fear of performing the surgery.

So it can be done, but this approach is not for the faint of heart.

One other consideration is the PCIe bus bandwidth. On my server it's only PCIe 8x. Some research I did awhile ago told me that anything more than an HD 5770 might saturate the bus and provide diminishing returns, YMMV.

Finally, in Dell's case, I ran into a situation where Dell may not actually provide the full 75 watts to their PCIe bus. Check your server specs carefully to see if HP gives you what you are expecting.
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November 2, 2012 10:00:28 AM

Hi im in about the same position as yourself with the added constraints of a micro atx case where about did you connect youre homebrewed cable ? anyway its Good to know that im i with a chance of connecting the gfx card that i want Thanks
i3 2120 3.3 ghz/8gb ram/ 350w
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