Hello everybody,
 
I bought the other day this gpu (gtx970 ssc gaming acx 2.0+ 3975) and i have a problem with the power supply. 
It needs 6pin and 8pin connection. My psu has only one 6pin cable. The box of the gpu came with some cables too. One of them may turn 2 molex to one 6pin.
 
My question is this: may i connect the one 6pin to the 6pin slot and the other 6pin to the 8pin slot (without an adaptor to turn in 8pin)? and at what risk?
 
After doing some digging with google i got confused. People claim that connecting a 6pin cable to 8pin slot doesn't matter at all, whereas other claim that you need a new psu with 2 pcie 6+2pin.
 
My psu is 600w and 1 year old by the way. i use i5 4460, 8GB of ram, two hdds and a ssd.
 
Thanks in advance.

Sure, go right ahead and put the 6-pin plug in the 8-pin socket and give it a go..An 8-pin socket is backwards compatible with a 6-pin plug and won't hurt a thing..As long as it don't cough up an error at boot saying "Please power down and connect the PCIE cables" (or something to that effect), try it..It might fail due to lack of power under load though..If it works, it works and if it don't, it don't.
 
You need to get an adapter, but just using the 6-pin plug in the 8-pin socket might work in a pinch until you get one..And yes, definately do get one, there are many types available.
 
FWIW, my (170W) card that has one 6-pin and one 8-pin socket runs perfectly fine, all the time, using just two 6-pin plugs..Actually, when I was testing it a long time ago I forgot about it for about a week and never had a problem, even overclocking it.
 
Your card is a 201-watt card..It can get 75 Watts from the PCIe slot..A 6-pin connector is for 75 watts..75W x 3 = 225W, which is slightly more than what your card rates at..More on PCIe Supplemental Power Connectors here..Like I said, if it works, it works and if it don't, it don't.

bob16314
Sure, go right ahead and put the 6-pin plug in the 8-pin socket and give it a go..An 8-pin socket is backwards compatible with a 6-pin plug and won't hurt a thing..As long as it don't cough up an error at boot saying "Please power down and connect the PCIE cables" (or something to that effect), try it..It might fail due to lack of power under load though..If it works, it works and if it don't, it don't.
 
You need to get an adapter, but just using the 6-pin plug in the 8-pin socket might work in a pinch until you get one..And yes, definately do get one, there are many types available.
 
FWIW, my (170W) card that has one 6-pin and one 8-pin socket runs perfectly fine, all the time, using just two 6-pin plugs..Actually, when I was testing it a long time ago I forgot about it for about a week and never had a problem, even overclocking it.
 
is a 201-watt card..It can get 75 Watts from the PCIe slot..A 6-pin connector is for 75 watts..75W x 3 = 225W, which is slightly more than what your card rates at..More on PCIe Supplemental Power Connectors ..Like I said, if it works, it works and if it don't, it don't.

Whoa! are you sure about this? 
 
I would try it but i fear that something's gonna fried and i don't want problems. 

bob16314
Absolutely, positively, 1010% sure..An 8-pin socket is backwards compatible with a 6-pin plug, read the link..It may work in a pinch until you get an adapter..It will not hurt a thing, at all..I said I ran mine for a week like that.

Ok! thank you very much! 
I'll give it a try and i'll come back later to tell you what happened. 
 
EdiT: i read the article in the link you posted! It was really helpful (of course along with you!).

First things first. @bob16314 THANK YOU SO MUCH for encouraging me!!! 
 
Ok! here's what happened...
 
I plugged the two 6-pin cables, the pc turned on but this message came up "please power down and connect the PCIe power cable(s) for this graphics card".  
 
Then i tried something else. Gpu's box came up with an adapter Y that turns two 6-pin plugs to one 8-pin plug. 
 
I decided to use that one and i simply connected the remaining one 6-pin plug -the other 6-pin was connected directly in gpu's slot- to one of the two slots of the adapter (the other remained empty!) and it worked like a charm!!!  
 
I installed the driver and everything's ok for now. 
 
Can i play some games now or should i wait to get an adapter that turns 2 molex to 8-pin just for safety? 
 

Yeah, was kinda thinking that error would crop up.
 
Play games now and see how it rolls..You have a 201 watt card..75W can come from the PCIe slot itself and the remaining 126 watts come from the supplemental power connectors..A 6-pin supplemental power connector is good for 75 watts, an 8-pin for 150 watts..You're not overloading anything at stock speeds..Chances are you could probably run it like that forever..Basically what you have now is a 6-pin to 8-pin adapter, which may be okay as long as you don't plan on overclocking the card..A proper adapter would enhance stability, performance and overclocking potential.

A 600W PSU with only 1x6-Pin? Is the PSU 10 years old? :D

Wait a minute. Your GTX 970 SSC has an 8 pin and and 6 pin connector???? Mine only has two 6 pins. 

Lol, was sure I got a 3975 but got a 2975.

So far so good. Everything works fine. I didn't even have a problem running Assassin's Creed Unity.
 
Hopefully tomorrow my proper adapter will arrive.