(Under development)
Background
Resolving VRM shorts is a classic area of graphics card repair. In the simplest cases, it might involve identifying and replacing a single failing MOSFET. In other cases, there can be challenging secondary issues like other shorts and possibly extensive PCB damage caused by burned components. There are also cases where there is a VRM issue, but not a dead short. An example of this might be where there is a single faulty (but not shorted) phase, resulting in VRM efficiency issues (excess heat) and instability.
TODO Add VRM sketch
Symptoms Of VRM related Issues
- Shorts on any 12v rail (most typical)
- Performance and reliability issues (crashing under load, low VRM efficiency, excessive heat from VRM area)
- Visual defects in the VRM MOSFETs (bubble on top, dark spots, dimples, solder ball between pins, cracks, burns) TODO show examples
Tools
Essential (for simple cases)
- Multimeter
- Hot air station
- Flux, Solder, Kapton tape or foil to protect sensitive components
Very Useful (for advanced cases)
- PCB preheater (components sometimes require high heat to remove them, heating from underneath can help a lot and may reduce the chances of other components getting damaged by excessive heat)
- Bench power supply (sometimes it isn’t a case of just replacing a shorted MOSFET, some fixes require deeper tracing to detect other problems e.g. shorted capacitor)
- ESR Meter (these can be very useful in identifying the shorted phase)
- Dremel (sometimes components can be seized to the PCB, in these cases, it is safer to Dremel the component away rather than persist with heat)
Approach
1. How to detect,
2. How to identify the failing component,
3. How to remove,
Protect nearby capacitors and inductors from heat damage.
4. Testing short resolution,
5. Replacement,
6. final testing
Links to example graphics cards with VRM issues
- GT 1030 Gigabyte (Card B) (VRM Short – FIXED)
- Gigabyte RX 460 2Gb (VRM Short – short fixed, need to replace MOSFET)
- GTX 760 Ti 2GB GDDR5 Alienware OEM (VRM short – short fixed, need to replace MOSFET)
- EVGA GTX 980 Ti 6GB 06G-P4-4995-KR (VRM short identified)
- EVGA GTX 1080 (VRM short resulting in PCB damage)
- 6600 XT (VRM Short identified, complex case, PWM is an I2C one)
- SAPPHIRE RADEON R7 265 DUAL-X (VRM short identified, short resolved, need to replace DRMOS, card shows a picture)
- Zotac GTX 970 (The faulty phase was identified and removed with difficulty, needed Dremel – short resolved, pad damage, card displays picture)
- EVGA GTX 1070 (Had a 12v shorted DRMOS, now has a remaining 5v rail short)