Computer won´t turn on if Video card is connected to power

[victor.monteiro1981]

Hi guys, this is my 1st post;

Very frustrated here...
I have bought a machine less than one year ago, decent one...check below specs:

Intel Core i7-6700K 4.0GHz LGA 1151 8MB
Mobo Asus Z170 Pro Gaming Aura
4x RAM Kingston HyperX Fury DDR4 8GB 2133MHz
Video card Gigabyte N GTX980WF 4GB
SSD Sandisk 480GB Ultra II Speed 550-500 MB/s
PSU Corsair CS750M 80 Plus Gold 750W

So there I was playing a game 2 days ago, suddenly my computer shuts down. I tried to turn it back on, but nothing happened. After several tests I realized that if my video card was plugged to the power cables (a pair of 6+2 cables) the computer wouldn´t turn on, but removing those cables it would turn on (no matter if the video card was connected or not to the PCIe, I tried both situations).

Further testing, I realized that it was the left side 6+2 slot that was the problem, so connecting only the right side one it would make the computer power on (but of course the video card was not on, since its fans weren´t moving).

Ok so now i knew something was wrong regarding power. Either the power supply was damaged or the video card was.... so I got a multimeter and measured the 6+2 pins from the PSU, and all measured 12V ok... so then I starting measuring the resistance in the board, and realized that in the right side slots I had like 400 ohms, while in the left side I had 1.5 ohm. Does this looks like a short ciruit to you? Shouldn´t it be similar to the other slot (400 ohms) ? How come a normal working video card suddenly short circuits? Check the picture below to understand those measurements:

https://imgur.com/a/bmBQq

I read many threads here, but most of them are for new setups so I ignored suggestions like resetting cmos, update bios.

Do you guys have any ideas/suggestions? thanks

 

[Obakasama]

Complete guess. Maybe one power connector is saturated first before the other is?

More practically, as a desperation act, have you tried swapping the power cables around? Or perhaps other cables for the PSU?

 

[Math Geek]

you have 3 pcie slots on the mobo and 4 x 6+2 pin power leads. i'd try different combos of the power connections with the card in the top slot first. if none of them work, then try second slot with various power connections combos. this will tell you if it is a slot or if it is the psu.

obviously you want the card in the top slot if possible so check there first with other power leads. you have 2 cables with 2 x 6+2 pins each. try the other cable with its 2 x 8-pins and see if they work. the psu itself has 2 places to plug the pcie cables into it as it is modular. move the cable you are using now to the other output from the psu. see if that fixes it.

only through trial and error like this can you be sure what the issue may be. also try a different gpu if possible. this will let you know if your gpu is messed up or not.

 

[victor.monteiro1981]

Complete guess. Maybe one power connector is saturated first before the other is?

More practically, as a desperation act, have you tried swapping the power cables around? Or perhaps other cables for the PSU?

I´m not sure about saturating first, but connecting one of them (the one I suspect has a short circuit) is enough to prevent the computer to turn on (no matter if the other one is connected or not).

Yes I tried to use different 12V sources in the PSU, no luck.

I´ve been reading and I´ve seen some cases where the GPU short circuits for some reason, not sure if it´s some electronic component that failed and caused that...

 

[Obakasama]

Have you tried the other PCIe slot as Math Geek suggests? Slight possibility of certain pins being an issue within the slot itself.

 

[victor.monteiro1981]

Have you tried the other PCIe slot as Math Geek suggests? Slight possibility of certain pins being an issue within the slot itself.

thanks for all replies...did all mentioned tests, the board seems dead.... maybe it has overheated, I sent to a specialist. let´s wait...thanks again to all of you so far

 

[woahwoahwilly]

Have you tried the other PCIe slot as Math Geek suggests? Slight possibility of certain pins being an issue within the slot itself.

thanks for all replies...did all mentioned tests, the board seems dead.... maybe it has overheated, I sent to a specialist. let´s wait...thanks again to all of you so far

I'm going with your actions. You should try buying a new motherboard.

 

[woahwoahwilly]

I reccommend a build with an A10 - 7850k AMD APU until you get the thing fixed. Or did you already get everything working again?

 

[victor.monteiro1981]

the damn card was dead indeed... tried thousand tests, no luck.... i´ll never spend that amount of money in gigabyte cards again...thanks everyone