Hello,

First I have to apology for this post being in English, but I hope that you understand.

I have some questions about testing a GPU for a faulty chip:

1) Checking the voltage drop on PCI X16 with a multimeter

How big can the difference be here?
If I measure a voltage drop of 0.9876 V and the next measurement is 0.9861 V then how big is the chance that the chip is broken?

2) Using PC AGP PCI-E X16 Socket Tester something like this

This should basically work by lighting the LEDs on board with different brightness according to the resistance/voltage drop. Working chip - all LEDs have the same brightness, faulty chip - some LEDs are brighter/dimmer
then the others.
Has someone used it and how accurate it is?

3) Checking VCC of BIOS chip (8th pin)

How good is this method and what are the measured values here one should expect to see?
I just measured 2kOhm on a working GPU's BIOS 8th pin, is this normal?
I also tested some GPUs that showed anywhere from 0.9kOhm to 2kOhms of resistance on the 8th pin on the BIOS chip.

4) Using a regulated power supply and seeing if the PSU's short circuit protection kicks in when supplying power to the chip

Have heard about this method in videos, don't know if it actually is any good.

Are there any other ways that can be used to determine a faulty GPU chip?

All the best,
Smoolae

Hey. By the numbers:
1. If voltage drop on PCI lanes differs more than 5%, GPU is definitely bad.
2. Accurate. But this only means that GPU's internal PCI-EX controller isn't shorted and GPU has proper solder connection with board.
3. This one signify about working DC/DC controller only. Voltages on BIOS chip can be 3.3 or 1.8 V. Current can be about 4 mA and less. Says DEFINITELY nothing about GPU itself.
4. This method works very well if you're looking for shorted capacitor and so. Putting current from PSU on shorted rail will result with overheating of shorted component. U must figure out what current can be set to every rail and monitor component's temperatures, preferably with thermal camera.


Most issues with consumer electronic consist only one of two reasons: improper (or missing) voltage and shortened connection (including internal connection in IC's)

Best regards.