You need good solder and repair skills and equipment.
I would say you need at least a Multimeter for troubleshooting electronic components and traces.
You need a fine point solder iron with lots of different types of flux and solders.
You need some type of graphics card holder or solder table or electronics stand of some sort to hold your PCB.
You need a well ventilated place like outside or an open garage to let out the solder fumes when soldering.
I would say you need an electronic microscope hooked up to a laptop so you can carefully inspect the PCB and components.
But Most IMPORTANTLY you need good eye sight and steady hands for soldering.
You need a heat gun for reflowing chips.
You need a desolder gun to desolder capacitors.

Once you have all these things then you can begin.

Some repairs are easy.
Like garbled video output. If the card is working but the video out put is garbled then it my just be a bad solder job.
The surface mounted chips solder welds have broken so you just need to reflow or drag solder the memory chips.
Reflow with a heat gun and some no clean flux should fix the broken solder joints.
Or you can drag solder with some flux and solder.

I have not see a bad ISA card.
But I have seen plenty of bad PCI cards.
Usually it is because of broken solder welds so the solder joints just need to be repairs.
This must have been a manufacturing process failure that plagued PCI cards in the 1990’s
Bad solder or flux or just a bad solder job process. But this solder job failure was a plague on PCI video cards.

Buy Voodoo cards run HOT and usually the solder joints breaks or they get damaged from over heating.
These are hard to repair. Some times you can just reflow the memory chips if the video is garbled.
If there is NO video it maybe that the GPU chip solder welds have broken because of excessive heat.
In this case some no-clean flux under the GPU and heating the GPU to 300f with a heat gun until all the flux has been evaporated may fix the problem. Just let the solder do the work of repairing the broken solder ball welds.

But you should always test all the circuits and traces and capacitors and mosfet and diodes and components first with a Multimeter.

The hard part is soldering small components.

Here is a video to see just how hard it can be.
https://youtu.be/7UBy7L3YzLg

I am not an electronic technician but most of the card failures I've seen between 2003 and 2010-2012 were due to problems in the soldering of the gpu due to thermal stress. Some also had capacitor problems but those were mostly low end and I have seen some cases of burned mosfets.
Personally, I avoid NVIDIA's 8000 to 600 I am not an electronic technician but most of the card failures between 2003 and 2010-2012 were due to problems in the soldering of the gpu due to thermal stress. some graphics also had capacitor problems but those were mostly low end and I have seen some cases of burned mosfets.
Personally I avoid the 8000 to 600 series (although the problem exists since the 6000 series) from NVIDIA (see the bumpgate https://semiaccurate.com/2009/08/21/nvidia-fi … tands-bumpgate/) and the high-end ATI 3000 to 5000 series, the rest is a matter of luck. Reflowing a GPU is a waste of time unless you have an impressive equipment and even then they do not usually last long.

Once we had a problem with a GIGABYTE NVIDIA 580 that failed and when it returned from warranty the board had a strange color so I thought the gpu had been reflowed. I put the Furmark on it and it lasted 2 minutes. After that we demanded the change for an ATI and the client never had problems again.
Those where dark days for the graphics cards.

Realistically, your chances will be pretty low. That's because GPUs from this era (early-mid 2000s) are very prone to BGA solder failure; because of the many heat cycles during its lifetime, the solder balls under the GPU die or the memory chips will crack and you will get screen artifacts or nothing at all.

One temporary fix for this issue is the ubiquitous "stick'em in the oven" approach, which will reflow all the solder joints. But, as you know, this will not last for very long, maybe a few weeks up to a few months until the card dies again. I used to do this oftenly for my 8800GTS cards.

The proper way would be to get one of those BGA stencils on eBay and a bag of new solder balls for GPUs. You will then have to remove the chip and clean the area out with some desoldering wick and install the new solder balls. As you would imagine, this is a very complicated task, usually done by very expensive machines/tools (such as one from Louis Rossmann's shop).

Knowing all of this, I would still buy them for $1, just because you never know what you're going to get, you could end up with easier fixes, like bulged caps or blown fuses if you're lucky.

Thanks for the tips and experiences, I decided to get into graphics card repairs and see what I can do with them. I need to practice my SMD soldering skills and it will be a good opportunity. I just bought 15 practice cards for a few dollars. Even if I can't fix a single one they still have heatsinks, fans and other components I can use later.
This guy also sells tons of faulty 775-939-AM2 boards for the same price (some as low as ￠75) but that's another topic.
I'll post my repair experiences here as I go along.

computerguy08 wrote on 2020-08-15, 09:34:

(such as one from Louis Rossmann's shop).

Just mail your cards to him. Tell him he can make a video with it if he likes :p

I mean, if he's competent and running a business...and you're willing to pay...

I fixed a few cards over the years.

4870x2 just needed a new fan.
HD7950 needed reflowed using a hot air workstation and some liquid flux.
various other cards with broken power connectors, solder cracks, bad capacitors.

Most dead cards stay dead.

Unknown_K wrote on 2020-08-16, 06:50:

I fixed a few cards over the years. […]
Show full quote

I fixed a few cards over the years.

4870x2 just needed a new fan.
HD7950 needed reflowed using a hot air workstation and some liquid flux.
various other cards with broken power connectors, solder cracks, bad capacitors.

Most dead cards stay dead.

I got a bunch of low end cards, many of them only have heatsinks on so I hope that those are less prone to overheating related GPU deaths.
The meanest of those cards is an X1600 Pro.
We'll see.

hwh wrote on 2020-08-16, 04:02:

Just mail your cards to him. Tell him he can make a video with it if he likes :p

I mean, if he's competent and running a business...and you're willing to pay...

That would be interesting, but not worth it.
By the time you paid for shipping and the repair, you could get another working card for the same money and keep the old one as well for spares.

Doing it yourself is cheaper and more interesting. I've seen individuals on YT do this by hand. If you have SMD soldering skills and parts, it's doable.

So far my hitrate is around 66% success.

Managed to fix a broken Voodoo 5 5500 PCI that was missing a bunch of components (mainly capacitors).

Managed also to fix a GeForce 256 DDR that was missing an utter load of tiny SMD components on the rear of the card (clearly had something dragged across it at some point).

I’ve also managed to successfully repair a GeForce 4 Ti4200 by replacing the dead memory with new old stock chips.

I have however failed at repairing a Radeon 8500 (though I’ve not given up on it yet - no display at all even though I’ve replaced a number of missing caps). And also failed at fixing a GeForce 4 ti4800.

I’m using a TS100 soldering iron with a selection of tips (micropencil, chisel, medium), a cheap W.E.R branded hot air station, and a duratool desoldering vacuum iron. Good lead based solder, good desoldering braid, and good quality flux is a must.

Yeah, Dont try to resell these defected and repaired cards online with out informing the buyer.
It's really NOT worth the trouble of repairing these unless you plan on keeping these cards for yourself.

It looks easy but soldering small components is very hard.

Intel486dx33 wrote on 2020-08-16, 11:32:

It looks easy but soldering small components is very hard.

I never sell my parts, too much hassle for too little gain.
I have a faulty Sapphire HD3850 with obvious memory failure, it has BGA RAM chips so that's already a big challenge.
This endeavor may stop before it starts.
Well, I wanted to do this.

Miphee wrote on 2020-08-16, 12:53:

I never sell my parts, too much hassle for too little gain. I have a faulty Sapphire HD3850 with obvious memory failure, it has […]
Show full quote

Intel486dx33 wrote on 2020-08-16, 11:32:

It looks easy but soldering small components is very hard.

I never sell my parts, too much hassle for too little gain.
I have a faulty Sapphire HD3850 with obvious memory failure, it has BGA RAM chips so that's already a big challenge.
This endeavor may stop before it starts.
Well, I wanted to do this.

I dont want to discourage you I would never try to discourage anyone unless it was unsafe for everyone.
But you really need the right equipment and skills And training to properly repair circuit boards.

So I would start with a proper education on electronics engineering and PCB and circuit board fabrication so you know what to do.

Intel486dx33 wrote on 2020-08-16, 14:43:

But you really need the right equipment and skills And training to properly repair circuit boards.

The equipment I have but zero experience with BGA chips.
The smallest part I fixed was a SOJ RAM chip.
I tried the heatgun method on the 3850 and it worked, the card is fixed. It could be temporary though but for now it's good enough for me.

Oops, it's a Sapphire HD 2400XT, not a 3850.
No wonder the card was dead, heatsink temp was 91 C° (196 °F). I installed a fan to get it down to normal levels.

Intel486dx33 wrote on 2020-08-16, 14:43:

I dont want to discourage you I would never try to discourage anyone unless it was unsafe for everyone.
But you really need the right equipment and skills And training to properly repair circuit boards.

So I would start with a proper education on electronics engineering and PCB and circuit board fabrication so you know what to do.

You don't really "need" any training, certainly for most board repair that is going to be simple component replacement rather than in-depth schematic analysis. So long as you cover the basics (like adequate ventilation), then the worst case scenario is you burn yourself or ruin an already dead card, hardly the end of the world. You do however need a methodical and logical mind.

If however you intended to run as a business venture, then yes, making sure you are talented enough to not ruin other people's hardware would be a great idea.

Look at Louis Rossmann for example, no formal training at all, yet leading his field (Apple logic board repair) without anyone telling him otherwise.

You can definitely "self-teach" and that "teaching" doesn't need to come from books/reference text.

I only once reballed memory chip by hand without proper hardware and it looked like that... https://drive.google.com/file/d/0B2rbHIj6SMlF … 0wtTjkxaG8/view
to desolder it/solder it I preheated the GPU board (it was laptop gpu) board on kitchen heater (i put it on a metal grate) and then used halogen bulb from the top, it worked fine afterwards but I would never want to do it again. But I know that professional setup requires a proper station, so I didn't want to heatgun it and juryrigged a setup with bottom heater, top heater, used flux and monitored temp with a probe. That card was very small so I didn't worry about it flexing too much, but anything bigger could break because of temperature difference. It was few year ago and today basic hardware should be cheaper and easily available.
I idenified which chip was broken by gently pressing it when video artifacts were appearing.

hwh wrote on 2020-08-16, 04:02:

computerguy08 wrote on 2020-08-15, 09:34:

(such as one from Louis Rossmann's shop).

Just mail your cards to him. Tell him he can make a video with it if he likes :p

that would be absurdly expensive and uneconomical considering the fact 2001-2007 cards are mentioned here 😜