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Old 06-17-2021, 03:52 AM   #1
taxxin
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Default [SOLVED] GIGABYTE GTX 750TI OC 2GB Screen Patterns

I picked up this GTX 750TI OC model here the seller states that the card works but when you install the drivers the output is completely gone. also the GPUZ reads 0gb VRAM

First thing I did was Reflash the bios, the bios read seemed okay but the problem was that the chip type could not be identified by the chip flasher tool.

anyways I checked for shorts and the card seemed to check out fine. So on testing it would boot up from bios screen but all the output display would be all messed up with white lines, To me this was a classic case of faulty VRAM. GPUZ picked up the card as VGA controller with only 1gb of ram

So i didnt even bother with trying to install drivers, with the little amount of memory that its using, it was already showing signs of distress. All the voltages seemed to be present, i knew it could really only be one thing, faulty vram or connections to VRAM

I tried a Reflow of the card doused in liquid flux, heated up the GPU chip and ram chips with 500deg of chinese hot air fury. till they boiled out.

after this i tried the card again and it got much worse. there were even more lines!

So took the card out again, I found that some components have been knocked off the back side of the card, one missing resistor around the unpopulated ram traces, and one capacitor that looked like part of the DVI SOCKET. I made a the best i could by measuring the resistance of the missing resistor pads, one side reading 1.3k and the other at 30 ohms, the closest ones i could find with similar resistances read about 1k ohm value.

So i went over to my scrap lenovo board and extracted a bunch of tiny resisotrs and MLCCs, and rehomed them in the 750ti.

Lastly i wasnt comfortable with the bios chip, it was a 20q25 chip and the bios files were about 160kb so i would have been safe with a 256kb chip. Lucky for me i found one in a scrap r7 270x board that i had lying around. it was a different brand but it had the same amount of KBs. So i pulled off the chip and reporgrammed it.

I reassembled the card and boom, no more patterns, it was going good! also both dvi ports were working where as before only one worked!.

Installed the latest drivers and GPUz gave me what i wanted to see, perfect stats.

Furmarked the card for a few hours and everything including temperature seemed stable at 72deg max.

So im quite happy but i dont actually know what combination of repairs actually sorted the problem and whether or not other components are still missing on the back?

Anyways its been a while since ive posted and I thought i might be helpful for someone with similar problems.
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Old 06-18-2021, 02:54 AM   #2
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Default Re: [SOLVED] GIGABYTE GTX 750TI OC 2GB Screen Patterns

Thank you for this post, it's very educational reading other's success stories
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Old 06-18-2021, 05:00 AM   #3
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Default Re: [SOLVED] GIGABYTE GTX 750TI OC 2GB Screen Patterns

Quote:
Originally Posted by dicky96 View Post
Thank you for this post, it's very educational reading other's success stories
thank you Rich, Im just glad that I can contribute back to the community, there will definitely be more questions from me in the future
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Old 05-24-2022, 08:26 PM   #4
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Default Re: [SOLVED] GIGABYTE GTX 750TI OC 2GB Screen Patterns

Can you specify where to replace the dc component? I have the same status card
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