780i and PSU compatability issues...

DemonTraitor · 28 Feb 2011 at 11:49

I have an EVGA 780i SLI mobo and a new Coolermater 850W Silent Pro PSU.

I installed a GTX 295 and the PSU at the same time, and have had sort of GPU issues (in other threads), kernal driver not responding etc.

The motherboards 8 pin socket is configured (mobo orientation with 8-pin in top left corner), is:

(clip)
[ A S S A ]
[ S A A S ]

(the shape of the pins (square and arched))

The PSU, however, has 2 lots of 8-pin ATX cables (permanently connected to the modula PSU), configured as...

(clip)
[ A A | S A ]
[ A A | A S ]

(2 lots of 4 pins)
(positioned to line up ready to plug into socket and clipped)

so, how am I supposed to plug in the 8-pin ATX?

Meanwhile I have been using a MOLEX to 8-pin adapter cable, but have been having GPU issues (screen blanking and kernel driver not responding), but I put this down to a GPU problem... as nobody really had a clue.

The GPU problem was a pain, so I took out the GTX 295 ready to send to my son to test in his PC and put my old 8800 GTS in. All fine.

This morning, after a few days with the GTS in, I turn on PC, and it does not post, just sits there with HDD led on, no screen, then powers herself off after 30 seconds.

I remove case to find the mobo LED showing "FF" which appears as soon as you turn on PC, and a red LED near the CPU fan socket.

Done some googling, and found that it could be CPU overheating, or not sitting properly etc - but I have not touched the CPU. I then found someone had tried a different PSU, and his PC was all better...

So, I plugged in my old Enermax 500W and the PC boots fine. Plug in the new Coolermaster, and problems again...

So, do I have a general PSU problem, or is using the MOLEX adapter for the 8-pin ATX causing an issue....?

Why does the Coolermaster 8-pin not fit into my mobo ??

Any help will be muchly appreciated...

Demon

paradisiac · 28 Feb 2011 at 12:01

i would imagine the 2x8pin connectors are for gfx and not mobo and the 2x4pin are the mobo ones

Liquid · 28 Feb 2011 at 12:13

Hi,

Looking at their website here, the 6+2 pin(8 pin) connectors are only for the video card/s, sounds to me that the 2 x 4 pin that you see/mention are intended to be joined together for 8 pin connection to the motherboard(look at the CPU 4+4 Pin x 2 picture for reference). It should also be noted that despite having an 8 pin socket on the motherboard, it will work with just a 4 pin connection too, check your motherboard manual for details.

Those are strange symptoms you are having, and it could be a fault with the psu itself.

If the 8 pin is not fitting the motherboard then I would say it's the video card one you are trying and not the one to use.

DemonTraitor · 28 Feb 2011 at 12:16

there are no pins that match the mobo 8-pin atx
and the 2 x 8-pin dont match the gpu

Liquid · 28 Feb 2011 at 12:18

is it the correct model that I linked previously?

DemonTraitor · 28 Feb 2011 at 12:22

yes it is

Liquid · 28 Feb 2011 at 12:24

ignoring the two 8 pin coming out of the psu, it should have come with 6 x 6+2 pin connections, have you tried these?

Vtec9k · 28 Feb 2011 at 12:26

That's the first I've heard of incompatibility with mobo and psu. Those connections have been standard for years?

The 4+4 connectors are for the 8 pin mobo socket. The 6+2 pin connect to the graphics cards.

DemonTraitor · 28 Feb 2011 at 12:29

i am lost. none of the 6 x 6+2 will fit the GTX 295 6+2, how did i have it plugged in before????

paradisiac · 28 Feb 2011 at 12:30

coolmaster said:
M/B 20+4 Pin Connector x 1
CPU 4+4 Pin x 2
PCI-E 6+2 Pin x 6
4 Pin Peripheral x 6
SATA x 9
4 Pin Floppy x 1

it clearly states on coolmaster site that the 4+4 pins are for cpu(mobo) so either you have them the wrong way around, or the connectors are deformed on either the mobo or psu. and the 2 6+2 pins should also fit the gfx card, so something isnt right with something.

DemonTraitor · 28 Feb 2011 at 12:31

omg - i am bad

even though the pins are different shape to look at - they do fracking fit!!!!!!

paradisiac · 28 Feb 2011 at 12:34

DemonTraitor said:
omg - i am bad

even though the pins are different shape to look at - they do fracking fit!!!!!!

haha yeh, its easily done. so have you managed to get the 4+4 and the 6+2 pins to fit the mobo/gfx ok now?

Liquid · 28 Feb 2011 at 12:34

the leads hard wired and coming out of the psu are for atx and cpu and not for video at all, as pictured here on this page. The video connections are modular and have a black connector for video card at one end and grey the other end for connection to the psu. Also note that a 6+2 pin plug works and is useable in a 6 pin video connection, just offset a bit.

Liquid · 28 Feb 2011 at 12:37

DemonTraitor said:
omg - i am bad

even though the pins are different shape to look at - they do fracking fit!!!!!!

Damn was typing when this was posted lol. looks like you will be running soon then

paradisiac · 28 Feb 2011 at 12:38

upgrading is a nightmare, always soo keen to get everything up and running to play with you tend to miss the obvious.

DemonTraitor · 28 Feb 2011 at 12:40

jesus mary mother!!!!

when i first got new psu, and tried to line up the 4+4 for the 8-pin atx, i noticed they were different shapes as explained above... so i instantly thought, **** that, i am not going to try and plug them in...

the gpu power, i just plugged in without looking, as they were the only ones that would ever fit, and they slipped in nicely...

however, just now, trying to go through the cables trying to separate the gpu ones from anything else, i noticed the 6+2 gpu pins are different shape, even though they still fit cos of how the socket is made... i just got confused when looking at them properly for the first time why the squares and arches were not lining up visually...

i think i have just learned, after about 15+ years experience in building pc's you can look too closely at things - what a muppet!!!!!!

thank you everyone and sorry for wasting your time.

i just need to plug everything back in and see if i still get the original booting problem i had this morning.....

Liquid · 28 Feb 2011 at 12:40

paradisiac said:
upgrading is a nightmare, always soo keen to get everything up and running to play with you tend to miss the obvious.

know what you mean lol, but the joy when you sort it all out and it finally works is priceless

Liquid · 28 Feb 2011 at 12:42

DemonTraitor said:
jesus mary mother!!!!

when i first got new psu, and tried to line up the 4+4 for the 8-pin atx, i noticed they were different shapes as explained above... so i instantly thought, **** that, i am not going to try and plug them in...

the gpu power, i just plugged in without looking, as they were the only ones that would ever fit, and they slipped in nicely...

however, just now, trying to go through the cables trying to separate the gpu ones from anything else, i noticed the 6+2 gpu pins are different shape, even though they still fit cos of how the socket is made... i just got confused when looking at them properly for the first time why the squares and arches were not lining up visually...

i think i have just learned, after about 15+ years experience in building pc's you can look too closely at things - what a muppet!!!!!!

thank you everyone and sorry for wasting your time.

i just need to plug everything back in and see if i still get the original booting problem i had this morning.....

not wasting time, don't worry about it. Chances are if you were plugging in the video connection to the mobo, it probably is to blame for the erratic behaviour in your system. Hopefully it's not damaged. Let us know how you got on.

paradisiac · 28 Feb 2011 at 12:43

DemonTraitor said:
i think i have just learned, after about 15+ years experience in building pc's you can look too closely at things - what a muppet!!!!!!

thank you everyone and sorry for wasting your time.

i just need to plug everything back in and see if i still get the original booting problem i had this morning.....

soo true, doesnt matter how many pcs you build you will always miss the obvious, and because its soo obvious you tend to overlook it whilst diagnosing.
as for wasting people time, that is definatly not the case, as im sure you are not the first, and wont be the last, to do this, so it will help people, and at the end of the day, you will soon have a working pc that you can play with.