Hello,
Purchased two GTX980ti palit jetstream to learn something about GPU repair. Both cards came in with shorts on 12V PEX 6 & 8 pin. These are old GPUs so economically not viable to invest time & energy but for sake of learning I am going with it.
There's bonus of still somewhat relevant performance and SLI if I get them to work. Have all equipment needed for the job as I do repair stuff as hobby.
Long story short I traced all the shorts and replaced faulty parts. Don't have schematics for this specific board but to an extent concepts are similar vendor to vendor as core/memory have same needs. It seems to have reference power design with 8x DrMOS, 3 phase doublers and ON PWM controller (5V version).
1st run, replaced:
1. Power steering mosfets 7403 (switching 12V_F & 12V_PEX)
2. All DrMOS 6823A
3. Fuses 2x10 & 1x15A
4. Measurement after replacement core 3,5 Ohm when cold, mem 71 Ohm. Power rails 12V_F, 3V3_F, 12V_PEX6, 12V_PEX8, no shorts, > kOhm resistances
5. Vcore 950mv idle, checked PWM pulses on coils with the scope before and after boot to windows, extra phases were turning/on off
Card booted, windows installed drivers no error 43, all good. Installed GPU-Z all voltages on all connectors normal. Started a game, as soon as card switched to 3d it gave white smoke. PC turned off and the card burnt the same parts.
2nd run, replaced:
1. all from 1st run
2. 3x 81162 phase doublers
3. 1x PWM controller 81174 - no clear motive why as PWM pulses proven controller is working but had no better idea
4. Updated vBIOS to ensure no voltage mods
5. Installed MSI afterburner - set power target to 80% for safety, removed 0 value resistor for OVP & OCP unlock (to lock it)
6. Checked thickness of thermal paste as resistance drops with heat, maybe due heat issues
3rd run, thought perhaps 6823A from China are to be blamed, got SIC789 from Digi-Key and replaced all 8 DrMOSes. EVGA used this in their 5V PWM version of 980TI as well, same doubles, same controller, no reason this should not work. But ended with the exact same result. All was going well before starting the game. Game started and after few frames PC turned off. Short is back on 12V_PEX8 DrMOS shorted again (last one). It takes about 1 second for it to die so no way heat is an issue, core hot spot was at 42C during the issue. DrMOSes cooled with thermal pads and stock cooler attached. In fact I am writing this post with one still running... before starting a game. GPU assisted graphics such as in windows or youtube videos work fine.
There's nothing else I see wrong there other than possibly GPU core itself. Was/is this common? Most references I found conculuded issue was resolved with replacement of shorted parts. Mine (both of cards) produce repeatable failure pattern.
Regards,
M
Purchased two GTX980ti palit jetstream to learn something about GPU repair. Both cards came in with shorts on 12V PEX 6 & 8 pin. These are old GPUs so economically not viable to invest time & energy but for sake of learning I am going with it.
There's bonus of still somewhat relevant performance and SLI if I get them to work. Have all equipment needed for the job as I do repair stuff as hobby.
Long story short I traced all the shorts and replaced faulty parts. Don't have schematics for this specific board but to an extent concepts are similar vendor to vendor as core/memory have same needs. It seems to have reference power design with 8x DrMOS, 3 phase doublers and ON PWM controller (5V version).
1st run, replaced:
1. Power steering mosfets 7403 (switching 12V_F & 12V_PEX)
2. All DrMOS 6823A
3. Fuses 2x10 & 1x15A
4. Measurement after replacement core 3,5 Ohm when cold, mem 71 Ohm. Power rails 12V_F, 3V3_F, 12V_PEX6, 12V_PEX8, no shorts, > kOhm resistances
5. Vcore 950mv idle, checked PWM pulses on coils with the scope before and after boot to windows, extra phases were turning/on off
Card booted, windows installed drivers no error 43, all good. Installed GPU-Z all voltages on all connectors normal. Started a game, as soon as card switched to 3d it gave white smoke. PC turned off and the card burnt the same parts.
2nd run, replaced:
1. all from 1st run
2. 3x 81162 phase doublers
3. 1x PWM controller 81174 - no clear motive why as PWM pulses proven controller is working but had no better idea
4. Updated vBIOS to ensure no voltage mods
5. Installed MSI afterburner - set power target to 80% for safety, removed 0 value resistor for OVP & OCP unlock (to lock it)
6. Checked thickness of thermal paste as resistance drops with heat, maybe due heat issues
3rd run, thought perhaps 6823A from China are to be blamed, got SIC789 from Digi-Key and replaced all 8 DrMOSes. EVGA used this in their 5V PWM version of 980TI as well, same doubles, same controller, no reason this should not work. But ended with the exact same result. All was going well before starting the game. Game started and after few frames PC turned off. Short is back on 12V_PEX8 DrMOS shorted again (last one). It takes about 1 second for it to die so no way heat is an issue, core hot spot was at 42C during the issue. DrMOSes cooled with thermal pads and stock cooler attached. In fact I am writing this post with one still running... before starting a game. GPU assisted graphics such as in windows or youtube videos work fine.
There's nothing else I see wrong there other than possibly GPU core itself. Was/is this common? Most references I found conculuded issue was resolved with replacement of shorted parts. Mine (both of cards) produce repeatable failure pattern.
Regards,
M
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