During repair of broken PC hardware it’s usually pretty accurate way to determine if complex ASIC like graphics processor or CPU damaged by overvoltage or overheat by simple measurement of power node resistance.
To do so you will need to remove power inductors between chip and DC-DC VRM (those are usually row of big inductors, featuring multi-phase convertor) and measure resistance to ground on output node (chip side) using usual DMM in resistance measurement mode. You should get value in range of few ohms, depends on specific GPU.
Here’s collected data based on actual measurements of some operational hardware:
| Graphic card | GPU ID | GPU, Ω | DRAM, Ω | Vio,V | Vgpu 2D | Vgpu 3D | Vmem |
|---|---|---|---|---|---|---|---|
| NVIDIA GeForce 2 MX400 | 200 | ||||||
| NVIDIA GeForce 4 MX440-8x | 13-23 | ||||||
| NVIDIA GeForce 4 Ti 4400 | 12 | 138 | |||||
| NVIDIA GeForce 4 Ti 4600 | 10.8 | 137 | |||||
| NVIDIA GeForce 4 Ti4200 | 20 | ||||||
| NVIDIA GeForce 4 Ti4200-8x | 19 | ||||||
| NVIDIA GeForce 5900 XT | NV35 | 5,7-6 | 194 | ||||
| NVIDIA GeForce 5950 Ultra | 3.8-4.2 | 108 | |||||
| NVIDIA GeForce 6600 | 2-5 | ||||||
| NVIDIA GeForce 6600 AGP | 7.3 | ||||||
| NVIDIA GeForce 6600 PCI-E | 4.5 | ||||||
| NVIDIA GeForce 6600GT | 2.2-2.6 | ||||||
| NVIDIA GeForce 6600GT AGP | 3.2 | 15.2 | 1.4 | 2 | |||
| NVIDIA GeForce 6600LE | 5.1 | 130 | 1,3 | 2,2 | |||
| NVIDIA GeForce 6800 | 2.2 | ||||||
| NVIDIA GeForce 7600 | 7,6 | ||||||
| NVIDIA GeForce 7600GS AGP | 2.8 | 55 | 17 | 1.23 | 2.1 | ||
| NVIDIA GeForce 7600GT | 4,4 | 71,3 | |||||
| NVIDIA GeForce 7800GT OC | 3.5 | 50.5 | 1.25 | 2 | |||
| NVIDIA GeForce 7800GT PCI-E | 1.7 | 45 | 1.3 | 2.1 | |||
| NVIDIA GeForce 7800GTX | 3.1 | 56 | 1.25 | 1.5 | 2.1 | ||
| NVIDIA GeForce 7900GS | 1,37 | 27 | |||||
| NVIDIA GeForce 7900GTO | G71 | 2.6 | 31 | ||||
| NVIDIA GeForce 7900GTX | 2 | 25,6 | |||||
| NVIDIA GeForce 7950GT | G71 | 2.3 | 101.7 | ||||
| NVIDIA GeForce 7950GT AGP | G71 | 1.7 | 30 | 1.3 | 2 | ||
| NVIDIA GeForce 7950GX2 top | 2,25 | 33 | |||||
| NVIDIA GeForce 8600 GT | 6-8 | 105 | 1.4 | 2.1 | |||
| NVIDIA GeForce 8600 GTS 512 | 2.4 | 44.5 | 1.44 | 2.15 | |||
| NVIDIA GeForce 8800 GT | G92 | 1 | 63 | 1.12 | 2.1 | ||
| NVIDIA GeForce 8800 GTS | G92 | 1 | 61 | 1.18 | 2 | ||
| NVIDIA GeForce 8800 GTS | G80 | 1 | 28.5 | 1.27 | 1.9 | ||
| NVIDIA GeForce 8800 GTS | G80 | 0.7-1 | |||||
| NVIDIA GeForce 9600GT | G94 | 1 | 55 | 1.2 | 2 | ||
| NVIDIA GeForce FX 5200 | 7 | ||||||
| NVIDIA GeForce FX 5200 | 10.5 | ||||||
| NVIDIA GeForce FX 5600 | 17 | ||||||
| NVIDIA GeForce FX 5900 XT | 5 | 1.2 | 1.4 | 2.73 | |||
| NVIDIA Quadro4 980 XGL | 9.11 | 133 | |||||
| ATI Radeon 9800Pro | 15 | ||||||
| ATI Radeon 2600XT DDR3 512MB | 3.25 | 32.2 | |||||
| ATI Radeon 2900XT | 0.42 | 8.45 | 57 | ||||
| ATI Radeon 7500 | 64 | ||||||
| ATI Radeon 9100 | 35 | ||||||
| ATI Radeon 9200LE 64MB | 335 | 1.6 | 2.7 | ||||
| ATI Radeon 9600 | 8 | ||||||
| ATI Radeon 9600XT | 5 | ||||||
| ATI Radeon 9700 Pro | 8 | ||||||
| ATI Radeon 9800SE | 10 | ||||||
| ATI Radeon HD 4850 | 1 | 16 | 1.1 | 2.1 | |||
| ATI Radeon X1300 AGP | 10.3 | 77.4 | |||||
| ATI Radeon X1650 PCI-E | 2.9 | 86.2 | |||||
| ATI Radeon X1900GT | 1.9 | 17.3 | |||||
| ATI Radeon X1950GT | 1 | ||||||
| ATI Radeon X300 SE 128MB 64b | 4.44 | ||||||
| ATI Radeon X550 PCI-E | 5.2-10 | ||||||
| ATI Radeon X800 | 17.9 | ||||||
| ATI Radeon X800GTO | 3-5 | 14-17 | |||||
| ATI Radeon X800XL | 4 |
Also here are some newer card useful reference points, key resistance values measured with high-accuracy Keithley 2002 DMM on good working card:
| GPU | Voltage rail | Resistance measured | Nominal voltage |
|---|---|---|---|
| 1080 | NVVDD | 80-250 milliΩ | 0.64 VDC … 1.1VDC |
| FBVDD | ~97 Ω | 1.35 VDC fixed | |
| PEX | ~44 Ω | 1.02 VDC fixed | |
| MEMPLL | ~450 Ω | 1.80 VDC fixed | |
| 1080 Ti/Titan Xp | NVVDD | 40-180 milliΩ | 0.64 VDC … 1.1VDC |
| FBVDD | ~80 Ω | 1.35 VDC fixed | |
| PEX | ~80 Ω | 1.02 VDC fixed | |
| MEMPLL | ~460 Ω | 1.80 VDC fixed | |
| 980 Ti | NVVDD | ~1.5-5 Ω | 0.7 VDC … 1.21VDC |
| FBVDD | ~15 Ω | 1.50 VDC fixed | |
| PEX | ~200 Ω | 1.02 VDC fixed | |
| 980 | NVVDD | ~3.5-8 Ω | 0.7 VDC … 1.21VDC |
| FBVDD | ~30 Ω | 1.50 VDC fixed | |
| PEX | ~180 Ω | 1.02 VDC fixed | |
| 780 Ti | NVVDD | ~1.5-4 Ω | 0.8 VDC … 1.23VDC |
| FBVDD | ~55 Ω | 1.50 VDC fixed | |
| PEX | ~160 Ω | 1.02 VDC fixed |
Table 2: Nominal resistance on main power rails from good GeForce GTX cards
Modified: Sept. 19, 2017, 3 a.m.