Seller Note “When this card was working I undervolted the card to improve thermals. I was able to get clock of 1400 with MV1070. 85 degrees the card would thermal throttle. Thermals didn’t go above 80 degrees using firestrike with the undervolt.” (Seller also described short related behaviour when questioned)
Summary
- I have a semi-working PowerColor RX 580 4Gb (runs but crashes, will compare resistances against it)
- Resistances
- VCore – 1.2Ω
- VMem – 33.5Ω
- VDDCI – 23.3Ω
- Display Rail – 14.8Ω (expected more like ~21Ω)
- 5V – 15.5KΩ! (seems very high, expected ~4KΩ)
- 1.8V – 3.8KΩ
- 3.3V – 218.3Ω (this seemed a little low, but matches similar cards)
- 12V – K++Ω (slot) 0.6Ω (ext) Short on 8 pin
- Other anomalies accompany the short on the 8-pin
Investigating the 6-pin PCI short
The 5V LDO appears suspicious, as:
- On this variety of 580, it takes 12V from the 8 pin which is shorted
- It has an abnormally high resistance on it’s 5V output. Could be something else on the 5V rail stressed it.
I briefly measured the gate resistances on all the high-side VCore VRM MOSFETS, all appeared normal. This doesn’t mean there isn’t a problem there (very common with a pic-ext short), but at this point, I am suspecting something else.
I will inject some voltage into the 12V 8 pin inductor and see if much current is drawn and if anything obvious gets warm.
Even 1V draws about 8.8Amps and C542 gets to almost 60°C
I’ll try removing this capacitor. After removal, the capacitor was short. I replaced it and the 12V short is resolved.
Initial testing is positive! Need to run further tests. Still not sure why the resistances are unusual for 5V and display rail, but the card seems functional so far:
- GPU-Z render test looks good, no temperature spikes, and sensors looking OK.
- Kombustor HD – steady 59°C
- 3D Time Spy – Scored Good.
- Subnautica 30 mins – 69°C fans 36%, decent VRM efficiency ~90%
- Heaven HD Ultra – 1 hr, 69°C, running nicely @ 100% GPU load
Next, real usage testing and PC gaming.