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Help needed with GTX 295 electrical issue

Graphics Cards - General - www.overclock.net
So, couple months back I acquired a dual PCB variant GTX 295 off craigslist. Took it home, plugged it in for a bit, and it ran just fine right up until the system soft-locked while playing Portal 2. At first, i thought it was simply Portal 2 not agreeing with SLI for whatever reason, and I thought nothing of it.

Fast forwards a couple of months, and I pull it out of the box again so I can pit it against a huge pile of other cards I acquired, and on inspecting the card I noticed that the Host-to-NF200 lane 0 Receive-side traces were missing one of the 2 SMD capacitors (on the negative side of the pair). As I understood it, this meant that while that line could still receive data and thus still function, there was no differential signalling, and thus one slightly "off" signal on the still good half of the pair would throw the whole smash off and thus result in a soft lock. The system bios on the DX58SO board would still detect it as running at x16 2.0 mode.

Here's where the oddity/derp on my part begins.

I thought: "Hey, since its a missing SMD capacitor, why not try to pull one off a dead video card i have lying around and try to solder that into place?" Somewhat sound plan, except apparently when the original snapped off it took its pads with it, rendering a normal repair impossible. My alternative option ultimately ended up being soldering a thin wire directly from the PCI-E finger to a small solder bulb directly after the missing capacitor, thinking it might work without it.

I plugged it in, started it up, and it ran. HOWEVER, the bios detected it as running at PCI-E x8. It worked well enough though. However, the connection to the PCI-E contact results in a relatively large mass of solder that prevents full insertion into the slot.

Now, my questions are:

1. How precisely is the NF200 chip failing over from the bad lane? Is it shutting down the first 8 lanes and running on the other 8 or what?

2. (depending on the answer to the above) What would be the expected behavior should I decide to completely kill the Lane 0 Receive traces (remove the "repair" and remove the other still intact SMD capacitor, thus completely opening that circuit)?

Do note that the rest of the card is fully functional, and even without my crap repair job it will still boot up and run, so long as i kept PCI-E transfers to a minimum (no gaming or I/O intensive compute). My ultimate goal is to get it running without worrying about it soft-locking, either in compute or gaming.

Edit: just to prove that my "repair" does in fact force the NF-200 to X58 chipset link to x8 mode and that it will in fact run:

Warning: Spoiler! (Click to show)

Edited by Cyrious - Today at 7:47 pm '); }
Date: Jul 15, 2017   


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