Zotac GTX 960 2GB- 6pin PCIE Power not recognized

[thrinrot]

Hi all!
A friend of mine brought me a defective Zotac GTX 960 with a failing power detection.
Even though the 6 pin PCIe power cable is plugged in, the card says "Plugin PCIe power cable and reboot".

Since I have no schematics it is hard to find out the NVVDD_PGOOD trace.

I checked if the Controller (NCP81174) sends a Power good signal and the signal VR_RDY at pin 3 is high. So I assume the controller is not sending a bad signal (?).

I appreciate your help! :-)

[mon2]

Re: Zotac GTX 960 2GB- 6pin PCIE Power not recognized

Hi.

Is this a new card or was it ever working at one time?

[thrinrot]

Re: Zotac GTX 960 2GB- 6pin PCIE Power not recognized

Hi mon2,

thanks for your reply.

It was a "new" (edit: unfortunately out of warranty because of second hand) card that has been working.
My friend told me that he swapped CPU and after that his GPU had this error.

Already had a look if there are torn off components due to CPU cooler swap or something, but the PCB looks fine.

Maybe it is GND sense of PEX6_DT that is not working correctly, but unfortunately I have no idea how to check that correctly.

I already found out, that sense goes to the base of a transistor with 1kOhm resisor in line. But I am wondering how that should work - since emitter would need a negative voltage for current to flow, so that collector curent can flow.

I am a neewb in graphic cards repairs. As long as it is not a simple braindead MOSFET causing issues I am nearly lost. (Still searching for good step by step tutorials, but they feel really rare)

Thanks in advance!

[thrinrot]

Re: Zotac GTX 960 2GB- 6pin PCIE Power not recognized

Found out that both resistors R516 and R501 were defective.
After changing them to 2.7k Ohm (R501) and 10k Ohm (R516) Resistors, the card is back to live again :-)

[elsaanna]

Re: Zotac GTX 960 2GB- 6pin PCIE Power not recognized

Found out that both resistors R516 and R501 were defective.
After changing them to 2.7k Ohm (R501) and 10k Ohm (R516) Resistors, the card is back to live again :-)

Brother, do you have this sub-diagram, can I have it for you?

[vcaina]

Re: Zotac GTX 960 2GB- 6pin PCIE Power not recognized

Found out that both resistors R516 and R501 were defective.
After changing them to 2.7k Ohm (R501) and 10k Ohm (R516) Resistors, the card is back to live again :-)

Hi! This is really interesting. Never thought resistors could do this. What's the behavior of the resistor? Does it have low resistance or an open line? I'm a newbie and I got this idea that resistors rarely fail.