Repairing graphics cards

I've been trying to work out how to fix a stack of graphics cards I've got. The most urgent are a pair of Nvidia GeForce 6600s (just 6600, no following letters).

Alas, every thread on the topic seems to already have an obvious starting point, in the form of dodgy caps or heat discoloration or, in extreme cases, a trail of scraped-off components from the scrapping process. What do I do when there's nothing apparently wrong with them, apart from the failure to function as expected?

One of the other cards works, but has a cooling fan that sounds like a wood chipper. Where in the heck do you look to find a replacement for something so absurdly model-specific? Is there a way to fix the old one instead? (Not sure I'd trust it if there was, mind you.)

Any advice will be gratefully received.

Hi,

What cards are they - Apple branded or generic? Cooling on these cards could be pretty average and without decent airflow and cooling the core burnt out on a lot of these cards. You may also read about "bump gate" for Nvidia GPUs of the era but this was mostly 7x00/8x00 models. Also check for damage as in clearly missing caps and other components on your e-waste cards.

You can strip down fans to lubricate and renew.

Oh, they're not e-waste, that was an example taken from what other threads on here I've managed to track down. The two cards I'm most concerned with, the Nvidia GeForce 6600s, are Apple OEM cards for a Power Mac G5 dual core machine, and as such never had fans in the first place. When the first one started acting flaky, I bought another… which promptly suffered the same fate (just long enough after I bought it that I can't call it the seller's fault). I think if I can't find any other issues the thermal paste may need renewing, because I've got the G5 running relatively cool these days (for a G5, at least, they’re a bit toasty by nature).

Two of the others are likewise Apple OEM for Power Mac G5, but these are for the older model with AGP 8x slot. I'm not too worried about them, except in obsessive-completionist terms of wanting to fix the whole stack, because they only have maximum resolution of 1920x1200.

Lastly, I managed to find (this is from memory and may be inaccurate, I'm typing this while on my break at work) a Radeon X850 Mac Edition, likewise for the AGP 8x slot – that’s the one with a fan that sounds like a wood chipper. When you say that the fan can be stripped down, does it need to be popped apart with mechanical force, or are there usually screws with which to dismantle them? I haven’t been brave enough to try tearing the thing down yet, I was hoping to find a YouTube example or something first. (No such luck just yet, though I'm sure there are several.)