Nvidia 580's power debacle

[maximumpanda]

hey guys,

I seem to have run into an interesting issue while trying to build my new "dreammachine".

part1:
when i attempt to power up my tri-sli 580 gtx cards they will ONLY boot if they are connected to a 8pin + a 6+2 pin cable (card requires a 8 and 6pin power cables).

if i try and use a regular 8 pin cable + a regular 6 pin cable, nothing works.

part2:

my PSU gave me cables that attach to the PSU as 8pin, then are headed 6+2 with an extra 6pin coming off the 6+2. for a little now i have been using 3x those to power my 3 card (6+2 pins for the 8pin and the extra 6pin going right into the 6pin slot) and that booted just fine and worked, but i suspect that was not providing the power needed to fully power the cards and thus lead to games constantly crashing, computer freezing up and random screen blackouts. thus why i am trying to use dedicated 6pin connecters.
(what the 6+2/6pin head looks like

the side that connects to the PSU is a standard 8 pin pcie head)

im not sure if my royally screwing something up here for if the 6pin cables/psu connectors are broken.

system stats:

intel i7 2600k 3.4 ghz
mushin 2133 redline (16gb)
3x EVGA 580 gtx (3gb)
evga p67 FTW
silverstone 1500w psu

 

[beenthere]

You link doesn't work. Please fix that so we can see what you are using.

 

[maximumpanda]

You link doesn't work. Please fix that so we can see what you are using.

just embedded it as for some reason the link wont load right

 

[beenthere]

The GTX 580 under max load draws 317W or ~27 amps. on the 12v rail(s). Each of the Silverston 12v rails is reported to supply 25 amps. To balance the load you will need a separate 12v feed for the 8-pin and a separate 12v feed for the 6 pin connector on EACH Vid card because one 12v rail can not provide full power under max load. So to be clear you will need to use two separate 12v power cables/12v rails - to each Vid card.


http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_560_Ti/25.html

http://www.newegg.com/Product/Product.aspx?Item=N82E16817256054

 

[maximumpanda]

i assumed as much. but my problem is that if i used a 6 pin only cable (6 pin on both sides of the cable) nothing works. I NEED to use a 6+2 cable for the 6 pin otherwise nothing in my system works (fans on case dont even spin)

 

[maximumpanda]

still need help with this issue. again my issue is that using a 8 pin and a 6 pin cable in a 580 gtx makes NOTHING boot, motherboard lights pop up but no fans are going off and it wont post. but if i use an 8pin and a 6+2 pin cable or a 6+2 that has an additional 6pin coming off of it, they work.

the 8 pin and 6+2 pin method doesnt work because it requires 6 8pin rails on the PSU (i am running tri-sli) the 6+2 pin with extra head method doesnt seem to work as my cards are VASTLY underpreforming against benchmarks that i found of literally the exact same system (same clocks, Mobo, CPU, graphics cards (clocks/#of cards), os, memory) that guy saw an average of 200 FPS in the benchmark, mine came out at 23, that shouldnt be right in ANY trisli setup.