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Author Topic: iMac MXM card upgrade. R270x/D300- I think it could be possible  (Read 3525 times)
ZZZAC
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« on: March 12, 2018, 09:40:14 PM »

Hi, To introduce myself i am a hardware repair technician, i know little about programming but ive done a bit of reading in here and made a few attempts myself. I have a couple of different ROM hardware programmers, allot of rework equipment and the hardware kicking around to test all this stuff out.

Im always looking for new graphics cards to put in imacs, and took interest in fitting a HD6850 chip onto a 6970M GPU and the changes in the video bios necessary to make this work.

Just as the 6970M took the HD 6850 GPU, looking at them, i think the 7970M PCB would facilitate the r9 270X GPU. This becomes interesting knowing that the R9 270X shares the same device ID as Apples Firepro D300, and that people have got r9 270X to work in mac pros (i have a pair of D300's kicking around my workshop as well)

That means that as far as i can tell:
1: a working EFI is already out there for this card
2: Apple supports the device ID of this chip
3: The 7970M PCB will take the R9-270X Chip.

Obviously a modified Vbios and EFI would need to be created (i really dont understand where to even start with the EFI of these cards) but i cannot see why this wouldn't be possible.

Would someone more clued up than me be able to tell me if im missing anything critical that would cause incompatibility.
Thanks
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dukefawks
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« Reply #1 on: March 13, 2018, 12:13:23 AM »

I assume you want to fix the "trash can" mac pro cards. It is probably possible like I did with the 6970m to 6850 conversion with the 27" iMacs. Although I am not using that anymore as there are too many thermal issues. Now using M5950 Dell cards with modified 6770m VBIOS.

Thermal issues with the trash can will probably also arise as the R9 270 has a device ID that is not supported by the SMC and thus it will not read the thermal/current sensors on the GPU board. Same happened with the 27" iMacs but I hacked around that by attaching the ODD thermal sensor to the GPU heat sink. Luckily the system did not down clock the CPU as it does many times with missing sensors.

Lets first see if the GPUs will actually become available before thinking about messing with these. I have yet to receive one of these for repair so I have no GPU part numbers to check for availability.
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Rominator
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« Reply #2 on: March 13, 2018, 02:16:26 AM »

biggest issue here is how the displays get mapped

On nvidia cards it is DCB table, on AMD it is "port mapping"

Fact is, when I revolutionized Mac flashing it was ;largely a result of understanding DCB tables on Nvidia cards. If you took a PC 8800GT and added the Mac EFI you got a KP on every boot.

But if you adjusted the DCB table to match the Apple standard, (and a couple other things) it would work. But until the DCB table got understood, nobody flashed Nvidia cards.

In addition, the EFI inits certain ports, that are then either taken over by the BIOS or not. If the EFI and BIOS have different ports, you may end up with something on screen, or maybe not.

Nvidia EFI also had locks based on device id and board id and another 2 digit number.

Ability to run PCIE 2.0 was also defined in BIOS, not sure how that factors into iMacs.

This is why I'm pretty sure I could figure out an iMac Nvidia Mxm card or two. I would say myself or Netkas are likely the only ones outside of Apple and Nvidia who could do this. But I haven
't the space to have a couple 27" iMacs in pieces here. It's a pity as I'm sure there are some cards that would be perfect, but will probably never happen.
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ZZZAC
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« Reply #3 on: March 13, 2018, 10:55:22 AM »

I assume you want to fix the "trash can" mac pro cards. It is probably possible like I did with the 6970m to 6850 conversion with the 27" iMacs. Although I am not using that anymore as there are too many thermal issues. Now using M5950 Dell cards with modified 6770m VBIOS.

Thermal issues with the trash can will probably also arise as the R9 270 has a device ID that is not supported by the SMC and thus it will not read the thermal/current sensors on the GPU board. Same happened with the 27" iMacs but I hacked around that by attaching the ODD thermal sensor to the GPU heat sink. Luckily the system did not down clock the CPU as it does many times with missing sensors.

Lets first see if the GPUs will actually become available before thinking about messing with these. I have yet to receive one of these for repair so I have no GPU part numbers to check for availability.

I do imagine it will have all the same issues as the 6970 conversion.

I do have a trashcan arriving today and an extra pair of GPU's, The D300's have 6810 device id's just like the r9 270X desktop cards, iirc they are also 215 chips.

But your right, the imac's will not support the D300's due to the imac not support that particular device ID
Thanks
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Rominator
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« Reply #4 on: March 13, 2018, 02:09:10 PM »

That...and the 6,1 doesn't have MXM cards.
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ZZZAC
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« Reply #5 on: March 14, 2018, 10:55:30 AM »

That...and the 6,1 doesn't have MXM cards.

I know that, i just think it would be possible to build a MXM card for a iMac 12,2 using a alienware 7970M  MXM PCB and a R9-270X chip
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Rominator
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« Reply #6 on: March 14, 2018, 09:52:30 PM »

Are you planning to desolder the BGA core and swap?

I don't understand what the point would be. Maybe I'm missing something?

They are very similar cards and seems like a lot of bother to just end up with a similar card.
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ZZZAC
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« Reply #7 on: March 24, 2018, 11:58:18 AM »

Are you planning to desolder the BGA core and swap?

I don't understand what the point would be. Maybe I'm missing something?

They are very similar cards and seems like a lot of bother to just end up with a similar card.

Yes, well that was the idea, I thought by fitting a chip that has an the same device ID that a native mac pro ships with, that it would be easier to get working properly, but i guess the main issue is the display routing anyhow?
Thanks
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DarthnVader
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« Reply #8 on: April 14, 2018, 01:10:56 PM »

Custom ROM's for graphics cards often only get done when it will create a marketable product. iMacs are just far too difficult for the average end users to disassemble and reassemble, shipping costs can be prohibitive, and MXM cards are not really available in any quantity to make it a real option for value added resale.

   
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Rominator
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« Reply #9 on: April 15, 2018, 01:53:46 AM »

You are 100% right.

What's sad is that I'm pretty sure the GT650/GT750M iMac EFI could be used to make other Kepler MXM cards work.

I actually bought a variety of cards and started work on it but finally lost interest. Real issue is the flashing/testing.

The only real way to do it would be an iMac with a PCIE/MXM extender so that the card would be exterior. The card itself would have a socket for SOIC-8 EEPROM. It would also need an external heatsink for use during testing.

After much testing we could find a few cards that would be perfect. Then testing in the machine for power/heat would need to happen.

Finally a product would be ready.

At that point used cards from Ebay and other sources would need to be bought, tested, flashed, tested again and finally prepared for sale.

Once sold it would be up to end user to install. I have found out the hard way that people will find many ways to screw up an install.The first GTX580 I ever sold the guy ran the 6 & 8 from a single 6 pin. Burned up 580 and screamed at me about it.

Most end users are hard pressed to install a standard GPU, the myriad ways an iMac install could go wrong could lead to misery for both ends.

This is why I have looked for an iMac repair shop in LA to develop with. They would provide testing gear, I'd write rom, they'd do installs.

Hard to imagine it working for standard end users, I think there would be much trouble.
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FaDaWay
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« Reply #10 on: April 26, 2018, 08:33:51 PM »

Rominator,
I can do this work for you and from France
I have all iMac as testing device and I have already many MXM card from PCs.
I'm sure together we will succed to modify Bios for iMac and help many people as it's really hard to find MXM cards for iMac now.
You don't need to be with me to flash and install card into iMac.

I send you a picture of one of my testing devices, you will understand that i'm ready to help you.

I have of course all the stuff to make an extender and flash Bios really quickly directly on the MXM board

I know also all kind of problems that you can find with iMac MXM cards so I can test with my tools and validate if a card can be used.



* Capture d’écran 2018-04-26 à 21.31.01 copie.jpg (90.05 KB, 900x842 - viewed 178 times.)
« Last Edit: April 26, 2018, 09:26:19 PM by FaDaWay » Logged
Rominator
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« Reply #11 on: April 27, 2018, 03:49:04 AM »

Wow.

That is certainly another way to make testing cards easy.

And it will solve cooling issues.

It seems you are serious.

Which Kepler MXM cards do you have?

Ideally thermal profile should be similar to card being replaced.
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FaDaWay
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« Reply #12 on: April 27, 2018, 06:04:10 PM »

Hi Rominator,
Actually I tried some cards really closes from Apple.

So today I worked on 6790M From Dell

When I use Apple Bios , I have a Boot screen , the iMac can pass the ASD and everything seem to work , exept of 1GB of memory instead of 2GB of course.
but I can't boot most of the time the result is a White Screen just before the desktop and some graphic issue with 10.7 OSX

« Last Edit: May 05, 2018, 09:52:33 AM by FaDaWay » Logged
FaDaWay
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« Reply #13 on: April 28, 2018, 04:30:01 PM »

So I have a black screen at boot with both of the last rom and with sound at startup.
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DarthnVader
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« Reply #14 on: May 02, 2018, 10:53:49 AM »

Remember those after market clear cases for the G4 Cube?

Why won't someone make them for the iMac, with access doors on the back.

Only instead of clear plastic, transparent aluminum. Tongue
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