Seller Note “Untested”
Summary
- No shorts, resistances looked ok except memory which is 76 Ohms
- Blank screen, main voltage rails appeared to be there
- vcore 0.99v 2 Ohms
- vmem 1.62v 76 Ohms
- PEX 1.08v 216 Ohms
- 5v rail there, high resistance
- The lights are on, but no one’s home! Need to establish GPU health
Memory is Hynix 7.0Gbps H5GQ2H24AFR-R2C FBGA(170ball)16Bank, 1.6V – So 1.6v is correct.
Since all voltages appear normal and resistances may be too, I want to check whether the GPU is healthy:
- BIOS
- VCC is about 3.3v
- Cannot see /CS chip select, data in or data out on oscilloscope
- Data in SI (pin 5) – None detected
- Data out SO (pin 2) – None detected
- Crystal frequency present SLK (pin 6) – I cannot see this on the chip pin, but the cystal is working.
- Need to double check BIOS circuitry, but could be a sign the GPU is dead.
- The BIOS contents can be read successfully using a CH341A reader
- PCI EX Checks
- REFCLK+- 3.3 MOhms – ok
- SMCLK/SMBUS for shorts – none
- Shorts on data lane capacitors – none
- Differences on receiver differential pairs (diode mode)
- 0.753v (lane 15)
- 0.734v
- 0.745v
- 0.752v
- 0.757v
- 0.758v
- 0.752v
- 0.752v
- 0.739v
- 0.856v
- 0.710v
- 0.717v
- 0.727v
- 0.755v
- 0.752v
- 0.752v (lane 0)
- Differences on transmitter differential pairs (diode mode)
- 1.137v (lane 15)
- 1.136v
- 1.149v
- 1.142v
- 1.143v
- 1.066v
- 1.132v
- 1.140v
- 1.111v
- 1.068v
- 1.142v
- 1.139v
- 1.145v
- 1.142v
- 1.135v
- 1.142v (lane 0)
- PEX capacitors good (check capacitance & ESR) – All capacitors seem in range. Not checked ESR.
- RESET Signal should go high – Reset always seems to be at 2.5v?
- Crystal appears to output a signal