8 pin PCI-E power connector mismatch

[don0819]

I just got a NVIDIA Quadro FX 5800 graohics card, and it needs 2 connectors. One of which is an 8 pin PCI-E connector. The computer's PS has a connector of this type, but the design of the 8 holes (square vs. not) do not match the design for the card's power input, hence the connector will not connect.

Is this common? I thought this would be standard. What is the best way to remedy this?

Thanks!

 

[delluser1]

The best way would be to first make sure you are looking at a pcie connector and not an 8 pin cpu connector.
http://www.playtool.com/pages/psuconnectors/connectors.html

 

[billiardicus]

The 8 pin you've got is not a PCI-E 8 pin, but a motherboard 8 pin connector. They look exactly the same except for the design of the square/round holes you mentioned. Remedy? Use molex or 6 pin to 8 pin adaptors. Some of these adaptors likely came with your GPU. If not, they're all over ebay.

 

[don0819]

Thanks, you are right about the connector. I'll check that out!

 

[don0819]

I have a question, I have spotted a 6 pin PCI-E to 8 pin adapter, does this look like a reasonable one?
http://www.pcpower.com/accessories/6-to-8-pin-adapter.html

Second question, my understanding (I am not aa power expert by any means), is that my video card will draw less power and not run at full speed if aa 6 pin PCI-E is plugged into the 8 pin connector slot. Does using one of these connectors solve that problem, ie is more power drawn somehow through the 8 pins? How does that work, since it's coming from the same place and through the 6 pin connector?

Thanks for answering my questions - I want to get this video card working optimally...

Don

 

[delluser1]

It should work fine ( no lack of power ), refer back to the link I provided and read up on the 8 pin pcie connector.

 

[don0819]

Yes I read that web page, it was very helpful. Not being an electrical engineer I was a little confused on how just adding two ground pins would cause the video card to draw more wattage. Is there some circuitry on the board that if the ground pins are absent it draws less power, is that how the board knows what kind of connector is present, and why a 6 pin would draw maybe 75W but an 8 pin draw 150W?

 

[delluser1]

Not an EE myself, but as I understand it, the addition of the extra grounds lessens the resistance allowing more current to flow.
Maybe retiredchief will come in and help with a better explanation.