Potential source of GPU artifacting found? (GTX 580)

[lchase2]

Hi all, I recently bought a GTX 580 3gb off of ebay for $15 knowing it had minor artifacting issues coming out of the DVI ports. The thing was disgustingly filthy (pretty sure never cleaned) and I really didn't expect much from the card, I just saw it as a potentially fun experience and chance to learn the in's and outs of a gpu (and potentially soldering).

The card run's much better than I thought it would, with only a minor amount of red horizontal lines appearing across dark colored objects and backgrounds, however these artifacts did not show up in screenshots. This led me to believe it might be the failing display outputs instead of the card, but upon dismantling for cleaning, I've found these two small bumps on the IHS of the GPU chip. Is this the source of the artifacting? Can a (proper) re-flow fix this? Otherwise, the thermal paste on the chip/heat sink was ancient, since the artifacting is minor is it possible a simple reapply and clean might do the trick?

In addition, I fully disassembled and cleaned the board with contact cleaner and arctic cleaner--the thermal pads were shot and i'm replacing them this afternoon. There doesn't seem to be any burn marks, blown capacitors or much corrosion to the board. I'm wondering if all the work I've done so far will potentially fix the problem, so i'll be testing that tonight, but if anyone can give me some insight i'd love to be cheap and not waste some MX-4 on something that needs a reflow.

 

[lchase2]

To add to the behavior of the card itself before tear down: The card would be identified by the display but the device would be stopped due to error 43 codes. I did a clean uninstall of all nvidia drivers and geforce experience in safe mode, restarted and no artifacts existed with the GPU functioning on a generic VGA device driver. I restarted after installing the latest Nvidia drivers, and the artifacts were back, as was the error 43 code. I followed this with a clean uninstall again followed by downloading the most stable 580 driver, 314.12, but this time the artifacts never disappeared. The GPU never showed up in HWmonitor or MSI afterburner, but did show up in GPUz, albeit without the memory or clock info.