Gigabyte 1070Ti startup problems

[nrs250]

I am having trouble diagnosing a 1070Ti that will get to the windows desktop, then reboot and not make it back to the desktop.

When checking power rails I have:
12V
5
3.3
1.80
occasionally 1.0V but this is intermittent and since this is the PEX rail I assume that dropout of this rail takes the GPU down and crashes the card.

No shorts on any of the other rails.
Resistance is 60 ohms on the 1.0 rail.

I am investigating the uP1728Q.
I have confirmed that it is getting 3.3V at Vin on Pin3, 5V from 5V Rail at VDD on Pin2.


I am seeing 0V on EN intermittently and concurrent with loss of the 1V output obviously from the UP1728Q .

In diode MODE:

PIN 9: 0.60V to ground
PIN 10 (EN): SHORT

In Resistance mode:

PIN 9: 2.6 kOhms
PIN 10 (EN): SHORT

Advice needed here:

Change the UP1728Q?

Trace the ENable signal: PS NVVDD PGOOD

PS NVVDD PGOOD seems to come from a buck converter: UP9511

I am puzzled as to whether to investigate the UP9511 or change out the UP1728Q.

Any help or advice would be appreciated.

[benwaterson]

Re: Gigabyte 1070Ti startup problems

The PS_NVVDD_PGOOD signal doesn't appear to be pulled to GND via a resistor/cap anywhere between chips, so possible the up9511 is bad.

Is R697 resistor present on that board? If so then maybe check R710 and C589 (FBVDD enable circuit, Page 26 in attached).