Most GPUs from the last ~20 years use BGA memory chips. You would need to find someone who is experienced in BGA rework (Laptop/Phone repair place would be your best bet.)
Many of these places might turn you away though, as they probably would not guarantee a repair on such old hardware.
For the places that would accept the labor, they would probably charge by the hour. This can vary by the shop, but a computer store I used to work at would charge "general labor" at $70/hour for anything that was out of the ordinary (ie, not a pre-priced service).
It may cost more or less depending on if you go with an individual or a company.

BGA rework is a difficult skill, but not impossible to master given time and practice. Consider looking into the process, watch some tutorials, pick up some cheap gear to play around with.

the sad part about this is that there is no way to know which of the 8 chips are broken
so you have to replace them all, and that means more work, and more risk of something badly soldered.

if you had some way to detect which is the bad one, then it would be much easy

Cga.8086 wrote:

if you had some way to detect which is the bad one, then it would be much easy

It's not a sure-fire way, but there are methods to determining failed components.
When parts fail, they tend to heat up (or not heat up) differently than their working counterparts.

The expensive way to figure this out is to use a thermal imager and visually discern the outlier.

The cheap way is to pour high percentage (97% or higher if possible) isopropyl alcohol on the board and slowly ramp up the power to the board using a bench power supply. The heat from the chips will cause the alcohol to evaporate quicker on a shorted component.

If the chip is in a semi-functioning state, then you'd need some pretty special equipment to troubleshoot it. Although, it's probably best to simply replace all of the chips at once.

There is a way to tell which is messed up with 100% certainty, however it isn't affordable on a consumer budget. At work I routinely send circuit boards and microchips out for failure analysis (both destructive and non-destructive). It usually runs my company about $20k to have it done with a report that tells us what components to replace on the board. They also give you all sorts of cool colorized x-ray photos, electron microscope photos, etc. This is usually only done for boards or chips that are extremely rare/obsolete in nuclear control systems.

Depends entirely on the country and the work involved. Is it a large shop or just a guy with some tools and experience?
I can cite numbers but they won't do you good.
An EEPROM repair costs here $5 (getting and writing new BIOS on chip) + the price of the new chip if needed.
Standard repair costs are usually in the $10-20/hour range but prices are mostly fixed. You have a problem, you tell it to the technician, they give you an estimate. Decent places only ask for money if the repair is successful.

In my country you would have to pay between € 70-100 per hour for someone who knows what he's doing and has the right equipment.

Nothing. If I can't repair it myself - I sell it, give it away to people who can or scrap it if the value is low.

thanks for the replys

i did not know that faulty BGA memory that gives artifacs produces more heat than good BGA memory

in that case, with a heat gun temperature meter, that you normally find on a home depot could also work? just power on the pc with artifacting and point the laser to each memory, the ones with more heat are broken?

or sometimes artifacs can be seen with memory at normal temperature?

Cga.8086 wrote:

thanks for the replys […]
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thanks for the replys

i did not know that faulty BGA memory that gives artifacs produces more heat than good BGA memory

in that case, with a heat gun temperature meter, that you normally find on a home depot could also work? just power on the pc with artifacting and point the laser to each memory, the ones with more heat are broken?

or sometimes artifacs can be seen with memory at normal temperature?

When I've had a partially working card with video memory errors none of the chips were particularly hotter than the others.
If a video RAM chip gets very hot it is usually shorting out and is likely to keep the whole card from operating.
You can run video memory stress test clean enviornment to find the faulty adresses and from that possibly work out what chips are broken. I can't tell you exactly how to find the defective chip from an adress, I only know that in theory it's possible but I believe you need some documentation on the layout of your graphics card.

I try to repair it myself. If I cannot repair it, I stash it away for better times to come. I have a colleague, who is also into retro world, and he brings me components to repair, but I do not charge him anything. He usually gives me some retro components as a thanks.

Sometimes I pay around 20 to 30 bucks for good capacitors to repair old hardware.
It's a bit steep, but also a lot of fun. My Abit VH6T came back to life after a complete capacitor replacement and the next hardware will be my Dell UXGA monitor that started to flicker and also needs a bunch of new capacitors. I expect the replacements for that to be around 15€.

I would never pay hundreds in parts to get equipment fixed, though. The most expensive thing I've bought for my retro setup was the keyboard - a 122 key terminal version of the IBM Model M - and I only did that because I had one 10 years back and stupidly sold it. 🤣

I pay more for the equipment that helps me repair things, though - because it is very useful for all of my projects in the long run. For example, I got a double pump desoldering gun for 150$ and that has saved me so much time and headache, it was absolutely worth it. There's also a hotair reflow station on my agenda...got some BGA things that need fixing.

I was put off buying new caps for a few boards that need recaps after adding them all to the cart it was like 30€ worth of caps each board... so I'll probably wait until I actually get to build with them before buying more ^^
some dual CPU boards sure have a lot of caps on them, I don't really want to cheap out on them either though if I go through the effort of recapping them in the first place.

SRAM and DRAM and other types of ram don't have a limited amount of writes before they fail!
(E)EPROM's do. But for them, the limit is around 1 000 to 100 000 writes. And how often do you burn those anyways?

When i can repair anything myself, i'll do it.
If i can't, usually it's more worth to sell it to someone, who can and is interested.

Haven't had cases where i want something to be repaired for myself and can't fix it...

I pay zero dollars.

But the economist would say that I pay in opportunity cost; that is, I could have been working and making money instead of fiddling with old computers.

no € spent for repairs, i rather try to do it myself.

I recently restored a original Xbox console for a customer earlier this week at work, by replacing swollen capacitors on the motherboard and disassembled the optical drive to bits and cleaned out the dirt build up that jammed the tray mechanism and some gears from operating easily. Then ultrasonic cleaned the pulley wheel with gear and hand washed in dish soap the rubber belt to restore traction (no chemicals ever on rubber!). Worked well.

Good thing I had a junk TV, which was found at value village while ago, Samsung LCD TV's panel is partially damaged but sufficient for testing. Kept tv at work just for the occasional equipment that needs composite or component, I think VGA as well, inputs. Every one was impressed that I knew this would happen this way.

Cheers, pentiumspeed