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Author Topic: iMac 27 2011, and 6850 based on 6970M MXM Board with BootScreen. Work!  (Read 3410 times)
flashedBrains
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« on: September 02, 2016, 07:19:34 PM »

Dear Community, Mr. Rominator. and all who somehow knowing about EFI.
sorry for my bad English.

Today i finished frankenstein 6850, based on 6970M with (216-0811000)
as i know on Ebay or ALIExpress, china guys sold this chip as new for 20-35$
but, as it sounds its REMARK from 6850 (Code name: BARTS XT and Barts PRO)

for this moment, all sellers on ebay or ALI send remarkered gpu 6850/6870 (215-0798000) as new 6970M (216-0811000)

so, few days ago i soldered (215-0798000) on 6970M Board.

native 6970M efi bios booting ok, system up good. but no bootscreen.

diagnostic led says: 1-ok 2-ok 3-down 4-down. on system boot,
after booting into OSX, 4 led is ok.

about this mac says: AMD Radeon 6xxx 1024mb

so, i have idea about this,
if original rom dont know this 215-0798000,
maybe EFI ROM from 6850 for Mac Pro know good this chip,

and...................

yes.... he damn know this chip,
i flash rom with efi bios downloaded from netkas in thread 6850/6870 for Mac PRo
soldered to my 6970M board with 6850 chip

1.. led ok 2.. led ok 3.. led OK!! 4.. led OK!!!!

and iMac show me BOOTSCREEN. with normal screen size, image good.
--------------------------------------------------------------------------------
but Display Routing in 6850 ROM for MacPro incorrect for iMac
and then OSX Loading to Login, or Dock moment, how correct say this? i dont know.
okay, when EFI gave control to OSX Driver, i think - Display goes Black. Black Screen.

BootCamp too after (ALT option changed to Windows) goes to BlackScreen.

i think main problem in ROUTING DISPLAY.

we know, so iMac based only on DisplayProt.
1... its Main DP Connector on Board,
2... MiniDP on back side
3... MiniDP on back side

well, i think for all guys who need back his 6970M to live again for 30$
we need to help. and fix Display Routing in EFI bios.

i attached some image, and efi 6850 worked on iMac with Good BootScreen, but wrong ROUTING Display.


* 468072242.jpg (147.13 KB, 1280x960 - viewed 201 times.)

* 39.JPG (64.26 KB, 600x468 - viewed 217 times.)
* iMac27_6850_bootscreen_OK.rom (128 KB - downloaded 105 times.)
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dukefawks
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« Reply #1 on: September 20, 2016, 03:24:51 PM »

So I'm not the only one doing this!
So far I have the card working in Windows. I have edited the PC portion of the ROM to match the 6738 DEVID of the 0798000 chip. In windows the driver loads fine and reports HD6800 serie and everything seems to run good.

I used the EFI portion of the 6870 from here with Duckweed identity, bootscreen is good but indeed as soon as the driver in OSX loads the screen goes black and the fan goes on high.
I did try changing the DEVID in the EFI portion using the original Elodea, but that results in a black screen at boot of course.

I really want to get this working because these imacs have been piling up here for months. I did send Netkas a message about this, but I guess he is busy enough with other things.

$500 reward offered for a working solution to this!
« Last Edit: September 21, 2016, 04:17:03 AM by dukefawks » Logged
dukefawks
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« Reply #2 on: September 21, 2016, 02:19:28 AM »

Well I finally fixed this myself. Biggest headache was uncompressing/compressing the EFI, had to remove the header first.

Here is the ROM for the 215-0798000(HD6870) chip. Will still show up as 6970M in OSX, only DEVID will be 0x6738 of course. In Windows it will show up as a HD6800 series, so you need to install the desktop drivers and point windows to it manually.

This was tested on a 1GB VRAM card, 2GB version not tested yet will update once I have done so.

Lets see when these are on Ebay.....

* 215-0798000.rom (128 KB - downloaded 96 times.)
« Last Edit: September 21, 2016, 03:39:22 AM by dukefawks » Logged
Rominator
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« Reply #3 on: September 21, 2016, 06:20:11 AM »

Are you saying it works perfectly ?

It:s kind of unclear.
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dukefawks
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« Reply #4 on: September 21, 2016, 10:07:23 AM »

Yes, this works 100%. Not surprising though because the only thing done is changing the chip and in the BIOS changing the DEVIDs.
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Fl0r!an
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« Reply #5 on: September 21, 2016, 01:42:19 PM »

Nice! You should be able to change that 6970M string if you already managed to decompress the EFI, simple search & replace.
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dukefawks
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« Reply #6 on: September 21, 2016, 03:15:10 PM »

I don't want to change the 6970M string because that is when the customers are starting to bitch about a different video card, no one will notice the DEVID change.
In Windows you don't have that luxury, unless you edit the driver INF file. 99% of these will only be running OSX so I'm not too worried about the Windows issue.
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dukefawks
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« Reply #7 on: October 08, 2016, 01:26:44 PM »

Had some issues with newer revisions of the card and Samsung VRAM corruption. If your ROM chips has a purple dot you need to use this updated ROM. Please check your EFI version @0xFCC0 and compare if the version is the same!

* 215-0798000purple.rom (128 KB - downloaded 45 times.)
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dukefawks
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« Reply #8 on: October 09, 2016, 01:20:31 AM »

Also tested the 2GB VRAM version, here it is. The ROM chip will have a silver dot.

* 215-0798000silver2GB.rom (128 KB - downloaded 65 times.)
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fixandinstall
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« Reply #9 on: November 26, 2016, 01:58:04 AM »

Sorry if this is the wrong place to ask, but it seemed the people in this thread would know exactly what I'm asking for, so I hope you'll forgive me Smiley
We have an iMac with defective 6970M 1GB MXM; so we ordered a new card from Ali, which usually is without problems, but this time we received a card that doesn't originally belong to an iMac.
We noticed this instantly since the back plate was different from what Apple uses (was glued on and had nuts instead of the usual holes for Tork screws). After changing the backplate, we installed it anyway, but we only get a black screen. The imac seems to boot up fine though, since we can hear normal HDD activity. After a while when it's supposed to boot to desktop, it reboots, and does this over and over again. So:

- After researching the issue, am I correct in presuming the only thing we need to do to get the new card working is replace the rom chip with the one from the old card?
- If not, which other chips need to be replaced? (there is a very similar chip just next to it)
- Am I correct in presuming the ROM chip is the chip with the purple dot (in my case - not really a dot, more like a tiny paint spill)?
- If the part numbers of both cards are exactly the same, should I still check of the RAM chips are of the same brand or does this not matter? The new card is installed in the iMac so would have to remove to check the RAM chips. On the original card the chips are Samsung. Model nr of both cards is exactly the same, but original card has 'BLACKCOMB' printed on it, the new one does not.
- If this route should fail, or otherwise not be possible, is there an alternative way of flashing this card so it would work? Have read some things on here, but nothing concrete as to how to do this, what tools/software to use. Our expertise lies in hardware, so we would much prefer to solve it with replacing the necessary chips.

Many thanks in advance for all info you can give me!
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dukefawks
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« Reply #10 on: December 11, 2016, 01:38:54 AM »

You need to swap over the ROM chip. This is the 8 pin one with the purple/white or silver dot on the left.
I doubt the card will be new though, probably a baked/heat gunned failed one from a Dell. Will fail again in a few months, so good luck with it.
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dukefawks
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« Reply #11 on: January 13, 2017, 03:53:48 AM »

More bug fixes. The 215 chips seem to not support the power saving/throttling features of the 216 ones properly. This resulted in throttling under full load and a black screen on boot for 20sec. when a certain temperature was reached. Here are the fixed BIOSes (1GB and 2GB) with all throttling disabled, these are the only files that should be used.

* 6970to079800x.zip (169.57 KB - downloaded 38 times.)
« Last Edit: January 13, 2017, 04:01:21 AM by dukefawks » Logged
rookieme
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« Reply #12 on: February 14, 2017, 11:14:56 PM »

Very interesting topic.
So from where do you buy trustworthy 215-0798000 chips?
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cheebster
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« Reply #13 on: March 01, 2017, 04:06:07 PM »

I'm trying to follow here but i'm not so sure what needs to be done.

I have this 2009 imac, nice build with i7 16gb.. And defective video card.

Anyone knows what kinda card can be used and reflashed with the provided roms in this thread ?

I've searched aliexpress and ebay and there's a lot of MXM cards available, but what needs to be checked for compatibility, other than the EEPROM ?

Also, can the eeprom be programmed with an external programmer if it's a different generation than what i had stock in the imac ? I have a xeltek superpro 3000u and another good programmer of some other brand here.

I've seen there's different generations of card being used in the A1312 model imac, depending on the build year 2009-2010-2011, but are all of them compatible other than the eeprom ?

Thanks for any help
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rookieme
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« Reply #14 on: March 10, 2017, 08:09:46 AM »

The 2009 iMac can accept any apple iMac gpu from 2009-2010-2011 all long as it has the room to fit.
Also it needs the proper heatsing as there are differences.
You can also buy a non apple gpu that has same chipset & board & part arrangement and reflash it's bios with apple's correct one found here https://www.techpowerup.com/vgabios/?architecture=&manufacturer=Apple&model=&interface=&memType=&memSize=&since=
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