PSU has 4 pin and 6 pin connections, need 8 pin for GPU

Aug 1, 2018
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I have a 550W PSU with a 4 pin ATX and a 6 pin ATX connector but I'm not sure how to connect them to a GTX 1070 which needs an 8 pin connection.

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I have some kind of 6+6 to 8 pin adaptor but I'm unsure if that would work.

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One of the sockets appears to be missing a pin so is the idea to turn two 6 pins, or 11 pins into an 8?
Would attaching a 6 pin and a 4 pin be the equivalent of turning a 9 pins into 8?

If that's how it works then it sounds like if 11 to 8 is okay then 9 to 8 should be too but I'm really not sure.

Any advice would be greatly appreciated, thank you.
 
Solution
The 6 + 6 pin adapter likely came with your GTX1070 to allow the 8 pin connection it needs.
You would need two of the 6 pin pcie leads as shown in the left of your picture to connect.
The 4 pin connector is a ATX connector needed for some motherboards.
If the psu does not have two such 6 pin pcie leads, it likely does not have the amperage to drive them.
In theory, using a molex to 6 pin adapter might do the job, but I would not.
Evidence of the age of the psu is the 28a capability on the 3.5v rails; that was needed on very old processors.

A cheap PSU will be made of substandard components. It will not have safety and overload protections.
If it fails under load, it can destroy anything it is connected to.
It will deliver advertised...

DSzymborski

Curmudgeon Pursuivant
Moderator
What is the *exact* PSU and *exact* GPU? Adapters are very rarely recommended, for the simple reason that any recent PSU that actually ought to be running something that needs 8-pin connection will have an eight-pin connection. Now, there a very few older, but competent PSUs that only have six-pin connnectors that it might be a very short-term solution, but I'll never recommend this to be done without knowing the details. There are competent 550W PSUs and there are "550W" PSUs I wouldn't trust to power a bagel.
 
Aug 1, 2018
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Turns out the PSU was older than I thought, bought it in 2012 and ebuyer lists it on the invoice as "CIT Dual Rail 550W Fully Wired Efficient Power Supply".
The GPU is a EVGA GeForce GTX 1070 8GB SC Gaming ACX 3.0
 

DSzymborski

Curmudgeon Pursuivant
Moderator


Hard no, then. This brand is one the more notorious purveyors of some of the shoddiest garbage dressed up as a PSU. I would never hook up any GPU needing supplementary power to that power supply, whether or not they stuck an eight-pin connector on there. They could have the highest quality Japanese capacitors in there -- they don't -- and the config box itself guarantees that this hasn't even been a 400W PSU since the days of Pentium II.
 
The 6 + 6 pin adapter likely came with your GTX1070 to allow the 8 pin connection it needs.
You would need two of the 6 pin pcie leads as shown in the left of your picture to connect.
The 4 pin connector is a ATX connector needed for some motherboards.
If the psu does not have two such 6 pin pcie leads, it likely does not have the amperage to drive them.
In theory, using a molex to 6 pin adapter might do the job, but I would not.
Evidence of the age of the psu is the 28a capability on the 3.5v rails; that was needed on very old processors.

A cheap PSU will be made of substandard components. It will not have safety and overload protections.
If it fails under load, it can destroy anything it is connected to.
It will deliver advertised power only at room temperatures, not at higher temperatures found when installed in a case.
The wattage will be delivered on the 3 and 5v rails, not on the 12v rails where modern parts
like the CPU and Graphics cards need it. What power is delivered may fluctuate and cause instability
issues that are hard to diagnose.
The fan will need to spin up higher to cool it, making it noisy.
A cheap PSU can become very expensive. Do not use one.

Buy a quality psu as a replacement.
I like the Seasonic focus line.
Here is a quality tier chart:
https://linustechtips.com/main/topic/631048-psu-tier-list-updated/
 
Solution

DSzymborski

Curmudgeon Pursuivant
Moderator


Good choice! While it may feel a bit like piling on, power supplies tend to be one of the more poorly understood parts of a PC and the consequences of a poor one can be extremely negative! Nobody wants to see your 1070 die a horrible death or you be out $400.