General Category => Rom things => Topic started by: kruftindustries on December 07, 2014, 08:10:15 AM

Title: 7970m in iMac 11,1
Post by: kruftindustries on December 07, 2014, 08:10:15 AM
Hello all,

I recently purchased a late 2009 iMac 11,1 with some damage from a posting on a local site for cheap. I have repaired all the damage, the lcd display ribbon cable had been ripped off, pulling a few pads, luckily I was able to trace back to vias the pads were connected to, clean them off and solder the whole lvds cable to the logic board. There were a couple problems with this, white screen only, no boot from hdd or snow leopard dvd, only 2 diagnostic lights illuminated. Popped the gpu in the oven and reflowed, got 4 lights but still no boot. disconnected hdd and option key would show mouse cursor. popped in ubuntu 10.04 cd and got blinking cursor on black screen but nothing else, got me thinking and popped in windows xp cd and it booted, popped in win7 and viola installed fine (it would not boot if I selected efi with the cursor, but would when I selected "windows", still dont know whats up with that...)

Anyway I upgraded the cpu to an i7-870 (the 880 was a tad spendier for not much performance improvement) and purchased radeon hd 7970m as I wish to use this machine as a replacement for my current acer laptop with a 5650. crysis 3 runs only 20-40fps at minimal settings, titanfall does about the same but the card in the imac only has dx 10.1? double the shader cores and none of my games are playable... Anyway

so here I am, have an imac with windows 7, no efi boot and a 7970m gpu that it refuses to post with.

I have reviewed the MXM3.0 spec and if apple adheres to it, there should be no reason other than video bios/logic board bios why it would not boot.
I have probed around and we are getting power, the gpu should be operational but logic board powers it down after I'm assuming it reads info from rom and is not pleased with what it sees.

the video card is an alienware dell 7970m with 15.022.000 rom. Pm25LD010 128k? spi flash (according to my flash programmer, datasheets found online say 512k??)
existing video card had Pm25LV010 flash, also 128k, I have compared it with the apple 6970 looking for similarities and there are quite a few among the 3

the only main difference I can tell is the extra data after the 0xFF's and a handfull of missing or added data between them, there are a few contiguous chunks here and there that have changed, I can't tell what was apple's doing and what is due to architecture differences. wimbledon is fairly new but I was surprised to find so much in common between them.

Thus far I have tried:

Changing the vendor ID in the bios portion of the rom w/corrected checksum - still no boot.

I'm not sure if the gpu not getting 11.9v instead of 19v is an issue, but according to the mxm spec, it should be fine between 7-20v

I was in contact with macvideocards via email and he discussed with me how to get it going with osx after I get it working, and the difficulty of creating the efi bios for this creature, if anyone here has any tips/details that would help this project along it would be magical! I have yet to delve into the magical world of atom bios disassembly and the thought of it gives me frownie face but if it comes to it, I'm fairly dedicated and have some resources at my disposal. I'm sure this would be music to the ears of anyone else that wants this to happen, once more my relentless google searches involving imac and 7970m brought me only sadness and hints of mac pro.

Attached is the important stuff from my conversation with macvideocards:

The part below means vendor id of 1002 with device id of 6800

And as we can see in the AMD 7000 controller, that device id exists

so it “should work” minus boot screens

writing an EFI for it will be very tricky as there was never an iMac with 7xxx was there?

You should be posting all of this at Netkas or MR or TechInferno (if you aren’t already)

> On Dec 3, 2014, at 10:14 PM, Nicholas Kruft <> wrote:
> 02 10 00 68

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on December 07, 2014, 09:22:37 AM

I looked up the datasheets for the flash chips on my current 4850 and 7970m and found the pins are the same. Considered the ddr3 ddr5 memory timings, I swapped them, hoping I would get garbled video and the 3rd diagnostic light would illuminate or the imac would attempt to boot. Nothing came of it so I am now considering the possibility of power issues or a possible dead card. Does anyone know of anyone ever using an alienware 6970 with apple vbios for example or anything like this? I will need to try this again in the future with the logic board on the bench and probe the states of the mxm connector pins. I managed to find the mxm spec sheet on baidu with pinouts and other useful info.

: it turns out that these roms apparently have a mechanism to prevent post if the architecture of the firmware does not match the gpu so this wouldn't have worked anyway.

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on December 08, 2014, 01:58:35 AM
Another update:

I now have the MXM 3.0 electromechanical and software specifications, I will be making an MXM to PCIe adapter to connect these cards to my computer for testing. If anyone else is interested in this project, I can make an actual PCI card that fits in a computer case and it will be a lot cheaper than $4000 (the only place I could find that sells these things wants a minimum order of 10 cards...)

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on December 09, 2014, 02:16:40 AM
Attached is a front pinout of the mxm 3.0 edge connector derived from the mxm electromechanical specification I created after work today. I had to crop and reduce quality a tad to make the 1000kb 250kb upload window. dafuq >:(

Google drive link: Front Image (

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on December 09, 2014, 05:02:04 AM
And the back side:

Back Image (

Title: Re: 7970m in iMac 11,1
Post by: Rominator on December 15, 2014, 12:43:04 AM
Any luck with this? Somebody made these boards before, I'd love to get ahold of one.

Still hoping to find a facility in LA repairing iMacs would would like to expand GPU offerings.

We have been able to add quite a few desktop cards because we tried. Same is likely true of MXM, I just can't start gutting iMacs here.

Title: Re: 7970m in iMac 11,1
Post by: blacksheep on December 22, 2014, 02:38:33 PM
7970M in alienware laptops are troublesome on hackintosh side of OS X. I didn't see a single success report.
Did a quick PC BIOS (from techpowerup) analysis and I'm 100% positive that it won't work in any iMac.
M17 use a tricky solution for AMD cards: GPU video signal goes to the display through iGPU. At least R3 does, so I presume that it's also true for R4.
OS X does not seem to support it this way, hence no success.
Connectors definition in 4850 and 7970 BIOSes are different as well.

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on December 29, 2014, 09:15:00 AM
I have not forgotten about the project, I have swapped a couple bioses now onto the eeprom still with no post. The graphics card does do something though for a brief moment but then shuts down so something must be working. It does shut down the imac if the card is allowed to get hot without the heatsink after a couple reboots so it is at least partially talking to the card. I did stumble upon some interesting information about the bios lvds/video output settings in a forum avout m17 r3/r4, particularly suggesting that the card does not work with the 3d monitor but if swapped for a regular monitor over lvds it works fine.

I have not shaken a stick at the pcie adapter though, I was hoping that I could get it to work without completely reverse engineering the whole situation and creating card interfaces. If there is enough need for one I can do my best creating one. Board fab leadtime for something like this is somewhat lenthy and I'm not sure I want to risk doing electrical damage if I don't cross my t's and such (I still don't know where that extra reserved pin went from the mxm spec to the card I used for the pinout...) I may just have to yank the logic board out of the imac and figure out what connects where and probe around on the signals of the working vs non-working. It could be a simple output configuration issue like with the m17 and/or perhaps the imac not liking the bios mechanism thingy that seems to be the going trend in this field thus far.

I am desperate for titanfall / other dx11 games on this creature as the display is very nice quality though at present it sits next to my computer monitor used mostly as a Netflix tv for the girlfriend while I work.

That being said, it is the mxm standard card edge connector we're talking about here, and there really isn't anything special about the gpu, a desktop 7870 with "mobility" bios in it's eeprom. Do you guys think there is something that can be done with the desktop 7870 bios (fairly confident it's the same) as in use a mac pro vbios for the task? I mean, I got this iMac on craigslist for $200, dropped the i7 in it for about $170 and replaced the monitor totaling around $440. I paid nearly that for this gpu knowing this was uncharted territory but still, if anyone wants to hazard some guesses, I'm all ears. I will probably bring the mac to work tomorrow and probe around on it if time permits

Title: Re: 7970m in iMac 11,1
Post by: blacksheep on December 29, 2014, 11:45:34 AM
The problem is, that iMacs since 2007 don't use LVDS, what's perfectly reflected in their vbioses. You can swap eeproms for eternity, you won't make this card work. Head over Nvidia cards.

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on January 01, 2015, 12:38:45 AM
The iMac display is dual link lvds, you're telling me there is something between the display and the GPU?

Title: Re: 7970m in iMac 11,1
Post by: blacksheep on January 01, 2015, 02:13:50 AM
Examine iMacs vbioses and you'll understand what I'm telling you.

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on January 01, 2015, 03:34:03 AM
I recently emailed gpudriverdevsupport at amd requesting atombios documentation and resources specifically referring to setting up the dvi/lvds output a few days ago. I don't have any experience disassembling the gpu assembly although I do with mips and powerpc as I have to do this at work from time to time when we don't receive/clients don't have ip for products we are repairing and testing. Is it somewhat similar? I have mulled over quite a few bioses looking for what apple is doing special, I know there are some tables pointing to specific things although I don't have much documentation or solid reference to go off of.

I was only referring to the hardware, would you please enlighten me? It may make this project a lot easier :)

Title: Re: 7970m in iMac 11,1
Post by: Rominator on January 03, 2015, 03:51:24 AM
You are beating your head against a tree.

You need to read up mat insanelymac or tonymac about how ATI/AMD cards define display outputs.

It is hard coded in driver in a way that Nvidia isn't.

As a for instance, we never got EFI flashed 5870 to work anywhere near right.

Boot screen appears on DVI port but only in the pass-through VGA wires.

Most DP on these cards only work in a few OS versions, typically black in most.

There is a way to fix, but it is to patch each and every driver OS update.

Nvidia cards are much easier to deal with as the display outputs are defined in the EFI and BIOS, not the driver so much.

You are hoping for some lucky guesses, but I sincerely doubt that you will get anywhere this way.

If Apple had wanted PC cards to work easily, they could have made them that way. So you are fighting the will of Steve Jobs and the board of directors. You are also fighting a team of frightened engineers who were told that there had better not be an easy and/or cheap way to replace those cards.

I got a nasty fright when I noticed on the Nvidia device id lists that Mac versions of the "M" cards typically have a different device id then all of the other ones. So if that digit isn't changeable via the soft straps the cards are pretty "locked". May be possible to move a resistor to change device id, but pretty good set of barriers.

Title: Re: 7970m in iMac 11,1
Post by: kruftindustries on January 04, 2015, 12:41:36 AM
I was hoping to bypass a lot of that crap by not using OS-X since this thing refuses to boot it anyway. I don't mind loosing bootscreen if it's that difficult to properly modify the efi. I already purchased and installed windows 7 professional to utilize all 32gb of ram. If there is some way to utilize target screen mode without osx, I'm all for it as I have a decent gaming rig already I just don't want to waste the imac to simple tasks since it has the potential for much more, and I've made more complicated things work in the past. I would say the board of directors were responsible for neutering iMac's with monetary aims, of course. My macbook clamshell overclocked easily by moving some resistors around, surely in the in the spirit of Jobs, the video card can be upgraded by moving some bits around but time will tell. I'll bring the creature to work and listen to what the lines have to say and surely find a definitive answer. I don't want to sell the 7970m for a 6970m until I'm confident they are not compatible on a hardware level. I'll keep you guys informed!

Title: Re: 7970m in iMac 11,1
Post by: reukiodo on February 11, 2019, 01:00:39 AM
I know there are a lot of pessimism around this, but I would really like to see this work. If a GCN card can eventually work in an iMac MXM slot, I would love to upgrade as this would then allow all the older Macs to run Mojave better.

What became of your investigations?

Title: Re: 7970m in iMac 11,1
Post by: Tpluth on March 09, 2019, 01:11:57 AM
I've got a couple of these and I't sure like to use one in my iMac.