• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

Reference GTX680 repair help

Joined
May 20, 2012
Messages
128 (0.04/day)
Location
Slovenia
Hello! I'm looking for someone with a reference GTX680. There's a couple resistors missing on the board, more specifically around the Vcore controller.
If you'd be so kind and measure the resistances of these two resistors. With that information I'll hopefully be able to fully revive it.
The card posts but fails to install drivers.

 
Joined
May 20, 2020
Messages
74 (0.55/day)
I've been a long time around, never registered here but when I saw a fellow GTX 680 owner in distress and from my own country, I quickly hopped to it. :)
I've used an Iskra MI 7030 multimeter and unless other components skew measurement (I use this card, so I didn't unsolder the resisters) resistance for the upper on the picture is 3,3 Ohm and lower 286 Ohm (lower jumps around some - around 290 Ohm).
You'll know they're right when it shows such resistances when they're soldered on the board.
Qapla' ! :)
 
Joined
May 12, 2017
Messages
1,003 (0.81/day)
I've been a long time around, never registered here but when I saw a fellow GTX 680 owner in distress and from my own country, I quickly hopped to it. :)
I've used an Iskra MI 7030 multimeter and unless other components skew measurement (I use this card, so I didn't unsolder the resisters) resistance for the upper on the picture is 3,3 Ohm and lower 286 Ohm (lower jumps around some - around 290 Ohm).
You'll know they're right when it shows such resistances when they're soldered on the board.
Qapla' ! :)
Welcome to TPU.
 
Joined
May 20, 2012
Messages
128 (0.04/day)
Location
Slovenia
You're an absolute hero! The card works! :clap:
Thank you so much for your time and effort!
 
Joined
May 20, 2020
Messages
74 (0.55/day)
Thank you for your welcome delshay.

Wow! Sweet! Have a shader-licious experience, madness777! :D
 
Joined
May 20, 2012
Messages
128 (0.04/day)
Location
Slovenia
Ok so it turns out the various missing components on the backside weren't the only issue. There was a bad transistor that was making the VMEM voltage go haywire which bricked 2 memory chips.
Funnily enough, removing the transistor didn't have any effect on the functionality of the memory VRM, it just worked, so I spotted out the two dead memory chips, removed them and replaced them using higher specced chips from a dead GTX780.
Don't even know what I was thinking but it managed to boot, install drivers and actually run 3D loads. I tried messing with memory frequency but it didn't like it one bit. Core overclocks normally!

Here's a picture of the repaired card.
You can see the right bank>top chip and the top bank>left chip



And a FireStrike score with a mild Core overclock, maxed powerlimit



This poor card has been through a lot but it's still huffin and puffin away, now with two different memory chips :roll:
 
Joined
May 20, 2020
Messages
74 (0.55/day)
Imagine that! Well - you'll know a good card by its core. :cool:
 
Joined
May 20, 2012
Messages
128 (0.04/day)
Location
Slovenia
Continuation:
It looks like the transistor that was removed controlled the 3D load voltage of the Memory.
With the transistor removed, the voltage stayed at 1.4v which by the looks of things is enough for the memory to run at stock (1500MHz) but not enough for any kind of overclock.
So I went on to figure out the VMEM voltmod to raise the voltage to 1.6v (stock 3Dload voltage), rubbed it with a pencil and now it overclocks nicely to around 1700MHz! :clap:
 
Joined
May 20, 2020
Messages
74 (0.55/day)
Wow - the good old pencil mod - I used that to overclock my Duron 600 to 900 and also 1000MHz back in the day. Good times.
 
Top