PCI-Express to Molex cable. Why can I not find one? - Techist - Tech Forum

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Old 01-25-2011, 03:11 PM   #1 (permalink)
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Question PCI-Express to Molex cable. Why can I not find one?

Hi there,

I have signed up to this forum in the hopes of finding a solution to my problem. About a month back, I bought a HD6870 for my new PC. This card requires two 6-pin PCI-Express ports from the PSU to run correctly. My PSU has only a single one of these, so I purchased a molex to PCI-E converter from eBay. Looks something like this:

http://www.binbin.net/photos/generic...n-pci-exp-.jpg

Upon receiving it, I noticed something odd. There were only 5 pins! I thought this must be common and the sixth pin must be uneeded or something, and so I tried to use it on my GPU anyway and it did indeed work, so I thought nothing else of it. However, after viewing benchmarks of certain games online I have found that my GPU is underperforming significantly in comparison. I thought that the unused pin may be the problem, and that my GPU was not receiving enough power. I looked around and bought another cable, this time from Currys. However, when I received it today I noticed ANOTHER thing odd about it. It's tiny! It's far too small to fit into my GPU, yet it is labelled as a standard PCI-Express cable!

So I came here to ask for help. Am I doing something wrong? Am I looking for the wrong type of cable? This is very frustrating and confusing.

P.S. I'm a UK resident, so no foreign shops! I don't really want to pay loads on postage, unless I really have to.
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Old 01-25-2011, 07:45 PM   #2 (permalink)
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Default Re: PCI-Express to Molex cable. Why can I not find one?

What is the Make and Model of your Power Supply?

When a power supply only has (1) pci-e power connector it usually because it's not capable of supplying enough power for (2) pci-e connectors.

It sounds like your power supply is only capable of supplying the bare minimum to run your card.
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Old 01-26-2011, 04:19 AM   #3 (permalink)
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Default Re: PCI-Express to Molex cable. Why can I not find one?

Arctic Power 700W PSU - With PCI-E, 4x SATA, 20+4.. | Ebuyer.com

It's that.
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Old 01-29-2011, 10:30 AM   #4 (permalink)
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Default Re: PCI-Express to Molex cable. Why can I not find one?

Here is an image to help better get across my point:



Notice the top middle pin is missing? All the ones I've seen are like that, for some bizarre reason.
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Old 01-29-2011, 10:46 AM   #5 (permalink)
 
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Default Re: PCI-Express to Molex cable. Why can I not find one?

Okay, odd.. but if i rfemember rightly someone had a galaxy card that had that config. How many wires are on it? 5?

|I found this: OcUK Value PCI Express 6-Pin to 4-Pin Power Adaptor for PCI-E Graphics Cards (RB-527) [RB-527]

But I'd call to confirm its all 6 pins
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Old 01-29-2011, 10:57 AM   #6 (permalink)
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Default Re: PCI-Express to Molex cable. Why can I not find one?

what are the rest of the parts in your system?

it might look like your rig is under performing compared with reviews/benchmarks if the rest of your parts are not as good as those used in those benches. many reviewers use OCed i7 systems, or atleast a c2q system, so if you're running on an old stock dual core or something, ofcourse you're not going to be getting the same fps.
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Old 01-30-2011, 09:37 AM   #7 (permalink)
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Default Re: PCI-Express to Molex cable. Why can I not find one?

Quote:
Originally Posted by Muffin Man View Post
what are the rest of the parts in your system?

it might look like your rig is under performing compared with reviews/benchmarks if the rest of your parts are not as good as those used in those benches. many reviewers use OCed i7 systems, or atleast a c2q system, so if you're running on an old stock dual core or something, ofcourse you're not going to be getting the same fps.


That guy has a very similar rig to mine, but he gets roughly twice the FPS. I have an i5 760 with 4GB of RAM.

Quote:
Originally Posted by patonb View Post
Okay, odd.. but if i rfemember rightly someone had a galaxy card that had that config. How many wires are on it? 5?

|I found this: OcUK Value PCI Express 6-Pin to 4-Pin Power Adaptor for PCI-E Graphics Cards (RB-527) [RB-527]

But I'd call to confirm its all 6 pins
Thanks, I'll contact them and see what they say.
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