Modding a Gigabyte 285GTX for Mac Pro?

[DIY_glenn]

Hi!

I did just finish my 2008 hardware -> 2006 chassis build and the machine seems to be running stable.

Anyways, I started thinking, this build has the 8800GT card, which requires one 6-pin PCIe power plug. The Logic board has two outputs, and I have a spare mini-plug to 6-pin.
I also have an unused Gigabyte 285GTX laying around, bought for a project years ago, but I never used it.
I know that the 285 is nothing compared to newer cards, but hey, it's something I already have, and the Mac Pro was later shipped with this card, which gives 70-100% more power than the 8800. And it requires two 6-pins, not 8-pin.

I want to keep this Mac as compatible as possible. I've tinkered with hackintoshes before, had great results, but I'm tired of the hacks&cracks. Therefore I was wondering if there is any way at all to make this card act as a stock Mac Pro 285GTX card? Soldering, flashing etc?
I don't want a black screen when booting, nVidia drivers that needs to be installed, or switching to the original for a reinstall etc, I'd like to have a fully Mac compatible graphics card.

Is this possible, and does anyone have a guide? I have great soldering skills, and no problems flashing the card. I'm probably never going to use this card for anything else than this Mac, but being able to revert back would be a good option, but not necessary.

 

[Fl0r!an]

I think I've seen a Apple OEM ROM for this card over at netkas, would be worth a try. I guess you'll have to solder a 2Mbit EEPROM on the card before flashing though.

 

[DIY_glenn]

Definitely sounds interesting!
So EVGA, MSI, Gigabyte, nVidia doesn't really matter? The ROM is the same?

The ROM is probably larger than the typical chip can store.
Is there a full guide on which chip to buy, how to flash etc? Anyone here done this before?
I've seen some forum posts mentioning "SST25VF020" as the chip they switched to. Can this be correct?

 

[Fl0r!an]

In general it's preferable to build your own ROM by combining the EFI part of the Mac ROM with the vBIOS part of your PC card. I've never done that for a GTX 2xx card, so I can't give you much advise on that.

Cross-flashing the whole Apple ROM file might work as long as your card is close to reference (same outputs, same VRAM size & type, ...). (Presuming Apple didn't include any locks to their specific card).

I'd look for a datasheet of the EEPROM on your card and get a similar, bigger EEPROM. I guess most SPI flashs in a SO8 package will work, but you might want to double-check with the list of supported EEPROMs in nvflash. I did the same some weeks ago with a GTX 570, was no problem.

 

[DIY_glenn]

Hmm. I was hoping it would be more in the terms of:
- "Switch out the original ROM chip with a larger one"
- "Flash the new chip with NVFLASH on a computer with USB-DOS"
- "Insert card in Mac Pro".

In terms of specifications, I think they're pretty similar;

EVGA Mac edition:


Gigabyte PC edition:

 

[Fl0r!an]

Sounds good to me

I don't think there's any public "how to flash a GTX 285", so you'll need to experiment a little. Maybe MVC will chime in, I guess this ancient card isn't relevant to his business any longer

Flashing can be done either in a PC or MacPro, doesn't matter. FreeDOS and nvflash is what you need, but you already now that. Make a backup of your original ROM, exchange EEPROMs and reflash the original ROM to the modified card to make sure everything worked as expected. Either do this blindly or with another card in place, but be sure to not brick your 2nd card in this case.

 

[DIY_glenn]

Hmm, that's true, another card...
Can the card being flashed be without the PCI-e connectors? I mean, it shouldn't really need that much power just for the flashing...

So you're saying that I should flash to original ROM first, then Mac FW?

If I replace the EEPROM, I guess I won't get any picture before it has been flashed. Blindly sounds risky, but also the same with the 2nd card. Is there a simple way to distinguish the cards?

The other card in the computer will either be the Mac with 8800GT, or a couple of other computers I have with 9800GTX+ and 460GTX (both based on the same chip as 285 I believe?)

 

[Fl0r!an]

I guess the card will refuse to initialize without power connectors, even if there's no load at all. I could be wrong though.

I'd flash the original vBIOS first to confirm the soldering was done properly. This will eliminate one error cause if you get problems with the Mac ROM later.
The cards can be distinguished in nvflash, forgot the argument though. You can output a list of installed GPUs with an internal index number which you'll have to use for flashing afterwards.

 

[DIY_glenn]

True, it sounds like a good idea to test with original ROM.

But yeah, as long as they are easily distinguishable, I'll have no problem doing the flash. I can probably power each GPU with one PCIe cable (I only have two on the PSU).

But how about the chip, I need to order one up, it seems like you used the "SST25VF020" as well? Only with a 'B' in the end?

I guess I'll have to disassemble the cooling etc. to get to the chip which I believe is located near the SLI-connectors. Can I use normal thermal paste for re-assembly? (Noctua NT-H1)

 

[Fl0r!an]

Yep, I just ordered a spi flash with similar specs. As I said, others should word to. The list of supported EEPROMs in nvflash is quite long

I guess normal thermal paste should work fine. I was lucky, the EEPROM was sitting on the backside of the card, so I didn't have to disassemble the whole thing

 

[DIY_glenn]

Yep, I just ordered a spi flash with similar specs. As I said, others should word to. The list of supported EEPROMs in nvflash is quite long

I guess normal thermal paste should work fine. I was lucky, the EEPROM was sitting on the backside of the card, so I didn't have to disassemble the whole thing

As long as this one works, I'm happy. It's on eBay for $3.90.

But it should be as simple as just that - Switch the EEPROM, and flash it? Not building a custom ROM etc?

 

[Fl0r!an]

As I said, building a custom ROM is preferable, but I've never done that for a GTX 2xx, so I can't give you any advise on this.

As long as your card is close enough to Apples one (and Apple didn't include any locks), flashing Apples ROM on your card should work.

 

[DIY_glenn]

So how would a custom ROM be preferable? What would be the difference?

 

[Fl0r!an]

With a custom ROM, you'd just attach the EFI to a perfectly working & compatible PC ROM, ruling out a lot of problems.

A PC card might differ in GPU clocks, ROM size & timings, output ports, fan control and other things from an Apple card, so crossflashing can result in strange behavior.
It's still worth a try, you said your soldering skills are good, so you'll always be able to recover a bad flash.

 

[DIY_glenn]

Aha, so as long as the 2Mbit chip with the Apple ROM seems to work, there's no benefit of using a custom ROM?

I actually found this on the forum:
"Test the First Flashed GTX285 ?"

Not sure if the chip I just ordered will work though, the one used was called:
SST25LF020

Mine was :
SST25VF020

Not sure what the L/V difference matters yet.

BTW I might be able to get a nVidia 285GTX, not really sure if there's any difference between Gigabyte and nVidia that matters though? They look completely identical...

 

[MacVidCards]

If the card has 1GB of RAM, stock Mac EVGA rom will be fine.

Pre UEFI cards much less likely to end up bricked.

Needs both power plugs, even to flash.

You will want to use EVGA ROM, the PCIE 2.0 switch on GT200 very hard to find, on 3,1 you need this.

 

[DIY_glenn]

If the card has 1GB of RAM, stock Mac EVGA rom will be fine.

Pre UEFI cards much less likely to end up bricked.

Needs both power plugs, even to flash.

You will want to use EVGA ROM, the PCIE 2.0 switch on GT200 very hard to find, on 3,1 you need this.

Great! Thank you for the info.
I guess I'll have to pull out some old PCI cards to use on my PC then. Otherwise I won't be able to power both cards (maybe I have a computer with onboard graphics...).

I'm not sure if this is pre-UEFI and whatnot...
What do you mean by "the PCIE 2.0 switch on GT200 very hard to find, on 3,1 you need this."?

I've seen some mentions of "2.5GT/s vs 5GT/s" but I'm not sure what to make of that.

The card is "Gigabyte GV-N285UD-1GH Rev. 1.0". Would it be better to use a nVidia GTX 285 instead? Doesn't matter?

I don't have any Mac roms available yet, so I'm not sure which to use anyways.

I checked with a camera, I found a chip by the SLI-connector, of course under the huge heatsink:



"Pm25LV512"
So I guess I'll have to order some thermal pads for reassembly after switching to SST25LF020A (I just got a confirmation that this will be sent instead of SST25LV020).

 

[DIY_glenn]

So I might've been a bit stupid here. But I removed the heatsink on the GPU, and removed the "old" thermal paste.
The thermal pads are still intact, but both the pads and the memory chips look a bit "sweaty". And of course there's a deep imprint in the pads.
Do I need to replace the thermal pads as well as the thermal paste? Can it be reused without cleaning anything?






As I don't have the EEPROM chip yet, I just put it back on the way it was (of course now without thermal paste) to prevent dust coming on the pads, IF they can be reused?

I didn't think of saving the ROM from the card... Can I put it in a computer, boot up DOS w/NVFLASH and extract the ROM without thermal paste... (But with heatsink)?

I thought it might be a good idea before removing the chip etc.

 

[BillyBobBongo]

I didn't think of saving the ROM from the card...

Maybe you can find it here - https://www.techpowerup.com/gpudb/

I'll leave it to the professionals to answer whether they'd fire it up and extract the ROM without thermal paste.

 

[DIY_glenn]

Meh, I have a small drop left in my Noctua syringe, might as well play it safe.
Another syringe is like $15 or so here, and I need more anyways.

Why take the chance!

What about the thermal pads? I've never dealt with that before.

 

[DIY_glenn]

Maybe you can find it here - https://www.techpowerup.com/gpudb/

Unfortunately there was nothing available for download there.
I found the Mac version of the card: https://www.techpowerup.com/gpudb/893/geforce-gtx-285-mac-edition.html

It seems to match the specs of my Gigabyte.
"Memory Clock: 1242"
Mine says 2484mhz, so I guess that's effective.

Anyways, when I click "Find compatible BIOS", the non-mac version comes up.

Edit:
Maybe I found the correct one on Netkas:

-GTX 285 EFI64
http://dl.dropbox.com/u/4133784/OrigRom/evga285m.rom
Can flash: GTX 285's, GTX 260, GTX 280 Unconfirmed (Soldering required. Only works on the 1GB/896MB versions. From what i've seen, GTX 260's with the plate underneath and GTX 280's will have an issue with the fan spinning wildly)

Is this the one?

Btw, I brought an old GTX285 home from work (thrown out like 40-50 computers with them) which I'll be using as a test. I'll desolder the chip (U6/U7? **1005*?), clean it, and solder it back on again. I've heard that the pads on the GPU's can be easily destroyed, so I'd rather try an old used card.

Even though I've (de)soldered a lot of SMD-chip before, the PCBs act very different to heat, and I got no experience with GPU's.

 

[DIY_glenn]

So I finally got the chip. I saved the original Gigabyte ROM, desoldered the old chip (destructively) and soldered in the new one. When I tested the card on my i3-setup afterwards (Intel HD graphics) the fan was running at 100%. I flashed the empty chip with the Gigabyte ROM, rebooted - everything OK.

I then downloaded the "EVGA285M.ROM" file, and tried flashing with it. I had to use NVFLASH 5.93.0.1 to not get any errors. I used the following command:

nvflash -4 -5 -6 -j evga285m.rom

And had to write "YES" etc. because of mismatch on the boards.

Anyways, 5 min later, the card is working with my Mac Pro, boot picture and everything. (One thing; it blinks black once after reaching OS X desktop, not sure if that is normal?)
I fired up Unigine Heaven, to test it out. It seemed to run stable, and with results that are probably correct. The temperature was listed at "38-40C" which seems ridiculously low, and can't be right. The grill at the back of the graphics card was very warm!!

So this is where I'm at now - I don't think BIOS/OS X sees the correct temperature of the card and adjusts the fan correctly.

Is it anything I can do with this? Any way to test if the card is working correctly etc?

(Btw. I get like 35FPS average in 1080p Minecraft, but I also did with the 8800GT. It might be a bug with Minecraft, Mac and nVidia, I get like 80FPS on my ATI MBP 2011.)

 

[Fl0r!an]

OS X can't read the temperatures of any graphics card, the SMC just lacks this functionality.
It's only a cosmetic issue though, the fan speed is adjusted internally in the card, OS X doesn't have to do that. As a result, Unigine displays some strange values as GPU temp.

 

[DIY_glenn]

Hmm.. That makes sense!
But the 8800GT boosted up its fan when powering on the Mac, the 285GTX doesn't, its fan is never more than the typical "idle speed". That's why I was worried, if the Mac EVGA-rom isn't 100% correct for my Gigabyte card...?

Everything else seems fine though.

 

[Fl0r!an]

That might actually happen since you cross-flashed the ROM from another card. Might be a good idea to monitor temperatures and fan behavior in Windows.