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mowl1ng

macrumors newbie
Original poster
May 9, 2021
7
1
Hello. I have a problem with Apple hardware and googled it around as usual, but after days of search and trial I am out of options. This forum looks like it's the holy bible of Apple stuff, and although I like to tinker with computers, I am a noob in Apple devices, so I decided to give it a try and ask you before giving up. Here's the issue:

I recently got gifted an old Mac Pro 3.1 early 2008 version by a friend, as "something fried" in it. It was full of dust, so I cleaned it all and built it back up. Quickly switched it on before the cleaning, to discover that the GPU [nVidia Geforce 8800gt] gave artifacts on screen, and that it was, in fact, overheating. Still, managed to boot antiX in failsafe mode and check the specs, but nothing more. Cleaned the gpu as well and solved the heat problem, but the artifacts were still there.
So I took another GPU, ASUS Geforce 9800 GT, which I recovered from a Hackintosh some time ago, thinking it would work straight away. How silly. So I learned about black boot screen issues with not supported GPUs, and made a plan. I bought an SSD on which I could just install the system AND the drivers for the new GPU using the old fried GPU, which still displayed a viewable image, and then boot from the newly installed system with the new GPU, with a black boot screen, but still. So I built a bootable El Capitan disk as it seemed the safest choice of OS, on another hard drive and booted it up from the boot screen. Take notice, i built the disk with a linux system, as I have no previous macOS installs, following the line of this thread, and it got successfully recognized by the mac EFI bootloader. When booting the install disk with artifacts on screen, it loaded the apple logo and the loading bar but at almost half bar the system reboots, chimes as it always does, reloads the disk and starts bootlooping in this cycle.

So the GPU is probably done for, I'm gonna try and troubleshoot it, but it's good for the oven I guess. It still boots antiX in failsafe mode, systemd-based distros seems like they all just hang, I thought of other ways:

- Tried booting the disk from the non-EFI GPU;
- Tried booting some linux live distros which generally boot straight away without user interaction from non-EFI GPU;
- Tried USB and HDD bootable disks just in case that was the problem;
- Tried with and without other disks in the slots;
- Tried letting live OSes boot without interaction;
- Tried do the magic trick of selecting the boot menu with options button and pressing Enter to boot with black screen;
- Tried with and without interaction to leave everything on and forget it;
- Tried booting correctly the antiX system from the old artifacted GPU then reboot switching GPUs;
- Tried resetting NVRAM which had the + battery metal holder broken which I repaired and put a new battery [they're standard, right?];

Anything I do, still I get a black screen on the new GPU. The craziest thing is that by doing some testing I accidentally popped in an old HDD which i thought empty which had a Windows XP install on it that booted and got me the 'windows hasn't shut correctly' black screen. So I'm sure there must be a way to have the GPU and the motherboard talk together.

At this point, I thought it was just a driver issue. I forgot to mention that the GPU fan is working fine. Sometimes it spins so slowly, that if you touch it stops, and then you have to spin it again, but most of the times it works fine. Don't know what that means.

So the problem now is that everything that doesn't boot from the old GPU, I can say it's the GPU that's fried, but everything that doesn't boot from the new one, I can't seem to figure out why.

Then I discovered the unofficial macOS bootloaders world, and thought that since they're made for PC graphics they could talk with the GPU new GPU, but no way. Tried rEFInd and rEFInd plus flashing them on a usb stick with but got the usual black screen any way I tried. On the old GPU they both run fine, and the same issues as before occur.
Tried Clover even if I read that it might be dangerous for neophytes as it should have integrated drivers for Geforce GPUs, same results.
I am looking at Chameleon for its <GraphicEnabler=yes> option which should work on 9800GTs but after these fails I'm not sure this is the right way either to get a working system.

So, right now I wouldn't say I'm out of options, but the thing is taking me more time that i would like to. Plus without satisfaction.

My questions are:

- Is there a way to get the macOS installer to load Geforce drivers during the installation process? I probably already even found the right ones, but I can only find guides on how to install drivers while in-system, but I don't have a system yet...
- Is my new GPU even supported? It should be apparently, but the fact that it's Asus customized and the lack of support makes me think I'm in bad luck. It's an Asus Geforce 9800 GT, google "EN9800GT" and it's the 512MB version with the fancy golden coolers.
- Is El Capitan really the best choice as OS version for it to work? I wouldn't mind switching if I knew there is a supported installer.
- Is the bootlooping process during install really due to my GPU? Probably yes, but I don't know whether bootloop is a familiar thing in the Apple environment.
- Would it make sense to try and boot a non-encrypted pre-made Windows/Linux hard drive on it? Just to see if it works. I have to make one, but I'd do it.
- If the GPU is not supported, can I at least install linux on it? It definitely supports the graphics card, but what if inside a Mac? And does it have to be already installed on a disk, as I can't get to boot live linux disks?
- Am I just ranting? Or am I actually making sense? I sincerely never got my hands on an Apple device until now and it's already gaving me a headache.
- Should I just get a compatible GPU? Is this driver thing so complicated and unsupported? As I said, I like to tinker and make things work, but this is becoming more and more of a wall to me.

I'd rather really just have a good old Debian system on it with all the nonfree drivers and things that make it work, but I can't even understand how to get the screen on. I suppose it's a MoBo-GPU misunderstanding, but if Windows XP manages to display then linux should be able as well.

Since I kept browsing and thinking and somehow I always came back on this forum, I decided to ask you, masters of Apple: what am I supposed to do now?

Thank you in advance for even reading until here and for helping me out. I bow to your knowledge.

Here some useful technical information:
Mac Pro 3.1 early 2008
[old] nVidia Geforce 8800GT 512MB
[new] Asus Geforce 9800GT [EN9800GT] 512MB
2x Intel Xeon E5462 @2.80GHz
Apple keyboard - so no shortcuts issues
6GB of what I think was 2 or 4 gigs of default RAM plus the other added by my friend

Now that I think about it, is it normal then when booted up the ram slots blink red a couple times? Because it does that while booting without the cover.

Again thank you for your patience, and I sincerely hope you have a solution.

Please ask if you need any additional information or pictures.
 
Last edited:
Tried rEFInd and rEFInd plus flashing them on a usb stick
Did you mean "RefindPlus" as a tool?
Many misspell this ... so not clear.

A working Geforce 8800GT should show a bootscreen with RefindPlus.
I believe it would with OpenCore as well.
 
Did you mean "RefindPlus" as a tool?
Many misspell this ... so not clear.

A working Geforce 8800GT should show a bootscreen with RefindPlus.
I believe it would with OpenCore as well.


Yes. RefindPlus shows successfully the boot screen AND the macOS installation disk. Still the disk doesn't boot due to the ruined gpu, at about half of the bar it reboots. After days of searching, my best option would be to flash the 8800GT bios onto my 9800GT, which has half of EEPROM space (512Kb vs 1Mb) and would require an EEPROM swap, which I believe I can handle. They should be similar enough for it to work. Just waiting for the tips for my soldering iron now...
Do you think it is a good idea?
Otherwise I'll just have to buy a used 8800GT... But trying to avoid it at all costs
 
No good idea. Perhaps it works.

Take a used 8800GT with 512MB VRAM, very cheap, models with green pcb are mostly reference-designs, have the 1MB-flash and can easy flashed to mac-version.
 
Do you think it is a good idea?
Otherwise I'll just have to buy a used 8800GT... But trying to avoid it at all costs
Sorry, I don't know enough about this to advise.
However, how did you conclude the issue is down to the GPU? Are you certain it couldn't be something else?
 
No good idea. Perhaps it works.

Take a used 8800GT with 512MB VRAM, very cheap, models with green pcb are mostly reference-designs, have the 1MB-flash and can easy flashed to mac-version.

Yeah, that will be my last resort once i bricked my old GPU. I'm not using it anyways, might as well give it a try. Not recommending it to anyone though.
As for whether it's a GPU issue, I managed to boot linux with artifacts and it worked fine, I don't know if it's an indicator but it strongly pushes me to say it's the GPU. Would there be any other way to check other hardware issues without a genuine GPU?
I might try again and output the dmesg onto a USB, so I can check it from my PC...

Anyways thanks to you all who answered, I will take my time to do the soldering job and think of different solutions, maybe checking the markets for some good prices...
If anybody comes up with other ideas I'd be extremely grateful as I'm still in a planning phase, but at this point I don't know how to get the GPU and MoBo to talk together...

Cheers
 
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8800GT are well-known for thermal issues, running too hot and higher failure-rate.

You should check your card in a Windows-PC.
 
8800GT are well-known for thermal issues, running too hot and higher failure-rate.

You should check your card in a Windows-PC.
Indeed, same issues. Artifacting and overheating. Fixed the heat with good thermal paste but it probably needs a chip reballing, which I have no interest in having it done. It literally burned both the aluminium case door and the ram box underneath it, there still are black marks which did not went away with cleaning. The GPU is definitely fried, what I'm wondering is whether I can't get the still-good 9800GT outputting anything because of compatibility issues, or because of some other component issue. By looking at the MoBo and everything else they doesn't seem damaged at all. Still planning on an EEPROM swap with the old broken one, worst of the case I should be able to put the original back on board and keep it as a PC card.
The most obscure thing to me is how is it possible that NOTHING outputs from the 9800GT, with or without boot screen, even when I boot Linux in both BIOS and UEFI mode, except for that crazy mistake when I did put in an old XP disk which got me a screen [read first post]. It thrills me so much I feel there is a way which is not buying a new GPU. Right now I'm waiting for the tools to do the swap job, but I'm still open to new proposals.
Again thanks
 
Ok, give it a try. I read that some (all?) 9800GTs are re-labeled 8800GT, perhaps the crossflash will work.

Be careful, if connectors and memory-size aren't identical, it won't work.
 
Ok, give it a try. I read that some (all?) 9800GTs are re-labeled 8800GT, perhaps the crossflash will work.

Be careful, if connectors and memory-size aren't identical, it won't work.
That is the reason why I wanted to try, rather than just buying a new one.

What do you mean by that? The swap would mean putting a 1mb eeprom on top of a previously-512b space, but I've seen successful substitutions even in this case. Are you talking about the card's VRAM? That's luckily the same 512mb... Please let me know as I will attempt the operation in the next days 👍
 
That is the reason why I wanted to try, rather than just buying a new one.

What do you mean by that? The swap would mean putting a 1mb eeprom on top of a previously-512b space, but I've seen successful substitutions even in this case. Are you talking about the card's VRAM? That's luckily the same 512mb... Please let me know as I will attempt the operation in the next days 👍
I might even try and flash the old 32bit 8800GT's 32bit ROM, which would be 512bytes and thus fit the actual memory space, but I've read that is for older Mac Pros, i/e 1.1/2.1 with 32bit EFI boot... is that correct?
So I don't really think it would work...
 
No, you need the EFI64-ROM if you own a Mac Pro 3.1 or newer. ROM for older Mac Pro 1.1/2.1 won't work, the Mac won't start.
 
Yep, I figured. I didn't want to try 'cause I was pretty sure. At this point, will attempt the magic swap, and update you guys as soon as I manage to break/fix something. Thank you all.
 
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