Seller Note “Gigabyte Windforce N770 OC: Not working, for parts only. No any idea what is wrong”
- The Ebay seller was either mistaken or lying! On inspection of the board this is not a Gigabyte Windforce N770 OC, but instead one of these https://www.gigabyte.com/Graphics-Card/GV-R929XOC-4GD#ov
- Screws in bad condition, some missing evidence of being dismantled in a rough way! Luckily cheapish, but not a good start in analysis..
- Thermal pads in very poor condition, dirty.
- Still, didn’t find any obvious shorts and the main resistances seemed in range, so perhaps there is hope yet.
- I have another RX290X in seemingly better condition Gigabyte R9 290X GV-R929XOC-4GD (Card B)
- PCI (measure at F4) – 4.15K
- PCI-E (measure at L601) – 2.1K
- PCI-E (measure at L602) – 39.6 (was 327 on my other 290X, so seems low?)
- 5V (measure at U400 or F400) – 3.8K
- 3.3V -398
- 1.8V (Created at U350, measure C357/8/9) – 213.6
- Display Rail (0.95V) (created at U300, measure at L300) – 104.8 (158 on other 290X, possibly a bit low)
- VCore (VDDC) (measure at any of 5 phases L502/3/4/5/6) – 1.1 (was 2.4on my other 290X)
- VDDCI (measure at L500/507) – 18.1 (was 35.4 on my other 290X)
- VMem (MVVD) (measure at L700) – 203 (was 242 on my other 290X)
- I find the lower memory and core related resistances compared to my other RX 290X a little concerning (VRM chip is ELPIDA W2032BBBG-6A-F)
- I also don’t know why fuse F4 is missing? The pads look poorly soldered, would be lucky if a fuse is all that’s wrong! Usually, they blow for a reason, but there is no short on that 12V as far as I can see…
PCB Missing Component / Damage
Here is the missing component area:
I don’t have a schematic, but a fuse can be seen in this position from a marketing photo:
It appears some kind of PCB repair has been attempted:
- Could be the pads were damaged/replaced.
- The area is sticky and patterned, perhaps flux residue.
I was initially concerned there was a nearly shorted capacitor on first investigation (C1326) shown below:
However, this capacitor is not actually shorted. I can now see one end is ground and one end is VDCCI (18 Ohms).
Apart from the rather low 12V (L602) rail, I think it’s worth replacing that missing fuse to see what voltages we can get. After doing so, strangely I can see most voltages apart from MVDD (shows 0.01V), which is similar if not the same as the fault on my other R9 290X! I think I will wait for parts and try replacing the VMem (MVDD) PWM controller. I have less hope for this card compared to the other one (lower resistances might hint at a core issue, no firm evidence), but it could still be worth resolving the VMem rail for the learning and chance it might work.