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Old July 6, 2008, 11:55 PM
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Default 6-pin PCI Express to single 8-pin

I was wondering if its safe to use a 6-pin PCI Express to single 8-pin cable connector? I read that the extra 2 pins in the 8 pin PSU connectors is for grounding. I was thinking about getting a new video card, but it requires a 6pin and 8pin power connector. My PSU has 2 6pin so no problem there, but the only 8pin power connector I have goes to my motherboard. The video card comes with a 6pin to 8pin power connector and was wondering if anyone is using them for their video card and if its safe to use?

The card I was thinking about getting was the Geforce 280. I have the Ultra 750watt Extreme Edition PSU. I just noticed that I would need to the the 4pin to 6pin power connector plus the 6pin to 8pin power connector as pictured here:

http://www.bfgtech.com/CMDocs/BFGTec...0260_Flyer.pdf

Is it safe to use supplementary power?

Last edited by no_pulse; July 7, 2008 at 12:29 AM.
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Old July 7, 2008, 12:24 AM
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Quote:
Originally Posted by no_pulse View Post
I was wondering if its safe to use a 6-pin PCI Express to single 8-pin cable connector? I read that the extra 2 pins in the 8 pin PSU connectors is for grounding. I was thinking about getting a new video card, but it requires a 6pin and 8pin power connector. My PSU has quite a few 6pin so no problem there, but the only 8pin power connector I have goes to my motherboard. The video card comes with a 6pin to 8pin power connector and was wondering if anyone is using them for their video card and if its safe to use?
You need both to work properly.

If your PSU doesn't have them, but a new PSU.
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Old July 7, 2008, 12:47 AM
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Well I assume this is your PSU:

Ultra Products - X2 750W ATX - Titanium w / UV Blue

With the 2 x 6 pin PCI-e plug one straight in and the other use the 6 to 8 pin converter socket and you should be fine. From what I have read the extra to pins are for ground. Your thinking seems sound and your PSU should be fine.
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Old July 7, 2008, 02:39 AM
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Originally Posted by Boldeagle View Post
Well I assume this is your PSU:

Ultra Products - X2 750W ATX - Titanium w / UV Blue

With the 2 x 6 pin PCI-e plug one straight in and the other use the 6 to 8 pin converter socket and you should be fine. From what I have read the extra to pins are for ground. Your thinking seems sound and your PSU should be fine.
Yes sir, that is my PSU. So you think I will be fine using the 4pin to 6pin and the 6pin to 8pin connectors? The thing I'm worried about is it being powered properly. If I use the supplementary power connectors, will it have the same power?
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Old July 7, 2008, 03:11 AM
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Originally Posted by no_pulse View Post
Yes sir, that is my PSU. So you think I will be fine using the 4pin to 6pin and the 6pin to 8pin connectors? The thing I'm worried about is it being powered properly. If I use the supplementary power connectors, will it have the same power?
no.
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Old July 7, 2008, 04:57 AM
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NO, not at all, you have 2 x 6 pin PCI-e socket those are the only ones you WANT TO USE! Look at the link there are 2 and that is what that Video Card needs!
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Old July 7, 2008, 09:08 AM
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Here is a great post on PS cabling.

All about the various PC power supply cables and connectors

IMHO these 8 pin plugs are just a cash grab. These things are over built.

I am not 100% sure what kind of adapters you are thinking of using. The PDF you linked to shows a converter that takes two peripheral connectors (the kind normally used to power hard drives) and adapts them to a 6-pin PCIe to power a video card. I would not suggest you use this with your power supply because the peripheral connectors are on a separate rail.

In general I would counsel against adapter spaghetti. Every connection add to the resistance and voltage drop in the circuit. Each extra bit of wire also increases voltage drop.
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Old July 7, 2008, 12:27 PM
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Originally Posted by Jack Rabbit View Post

I am not 100% sure what kind of adapters you are thinking of using. The PDF you linked to shows a converter that takes two peripheral connectors (the kind normally used to power hard drives) and adapts them to a 6-pin PCIe to power a video card.
Since my PSU only has 2x 6pin connectors, I was going to use them both in the adapter that converts 2x 6pin to 1x 8pin. And then I was going to use 2x 4pin connecters in the 4pin to 6pin adapter. Which is illustrated at the bottom right of this link: http://www.bfgtech.com/CMDocs/BFGTec...0260_Flyer.pdf

But as you and others have suggested, its not a good idea to use the adapters to power the card. Since I would need a new PSU just to power the Geforce 280 and that would be around $1000 for the card and PSU. Would have been a nice upgrade from 2X 8600 GT XXX.

I might as well wait for the 9800 GTX+ the next few weeks. Hoping they don't need both an 8 and 6 pin to power them. Anyone know if the new 9800 GTX+ will be any good?
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Old July 7, 2008, 01:07 PM
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Originally Posted by no_pulse View Post
So you think I will be fine using the 4pin to 6pin and the 6pin to 8pin connectors? The thing I'm worried about is it being powered properly. If I use the supplementary power connectors, will it have the same power?
From what I've read the 6pin PCI-e connector supplies up to 75W guaranteed, while the true 8pin connector on newer PSUs pumps about 145W guaranteed. Having said that I've also seen statements that the 6pin connector can supply more than the guaranteed 74W, in fact up to 115W or so. Your mileage may vary of course.

I am not sure how the power output of the 4pin vs 6pin stacks up, so I don't know if that's a factor in your case.

Some 280GTX cards come with the 6pin-to-8pin adaptor (BFG does if I am not mistaken), some (like my XFX) don't. In fact, my manual states that the XFX 280GTX does not support the 6pin-to-8pin adaptor and its use is not recommended.

So I guess you could do two things - either try the 280 with the adaptor thingie and see if your PSU can supply enough power, especially if you're running the card under a heavy load (like Furmark for example) or sell your PSU and get a newer one that has 8-pin PCI-e connectors.
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Old July 7, 2008, 07:39 PM
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Could someone recommend a good PSU that is modular and would be able to power the Geforce 280 for around $150 - $200?
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