iM 4,1-14,4 2011 iMac Graphics Card Upgrade

[lsdc]

(apologies if RTFFP)

I have iMac 12,2 with failed GPU.
I have sourced AMD WX4130 (Dell) as a replacement.

Aiming at OCLP/Monterey as I have on my old MBP and another stock iMac 12,2.

Gearing up for the operation

Q (Software): Is it possible to create the OCLP USB installer with the (replacement) AMD GPU drivers already in place by preparing the USB on another machine ? When I look in Developer Settings on OCLP (GUI 0.4.10) - the option to select a specific MXM graphics card is not selectable.
Is there a workaround?


Q (Hardware): I (only) have Arctic MX-4 paste, and I bought some 0.5mm copper shims.
Is another kind of paste really needed for the VRAM?

Thank you in advance for any advice.

 

[StreamVersus]

Probably, someone will help me there, i tried to modify .kext to get bigger brightness span, but after taht my mac os bricked + after NVRam reset, lcd becomes black, because of the boot arg, are there some method to recover .kext from backup i did before modifying, but i cant start mac os, or even recovery. Im using 880m

 

[dfranetic]

I tried to follow the same instructions for my 27" 2011 iMac with Quadro 2100 upgrade, and I ran into a snag. The keyboard isn't recognized during the Monterey install. It's recognized during boot to hold Option, it's recognized in the boot picking to select the USB EFI and then to select install Monterey, but once the installer starts, it won't recognize the keyboard anymore. Standard Apple Bluetooth keyboard, by the way.

Hint: Do you use stock BT module or have you upgraded it? (BTW: This is off-topic here...)

 

[phillytim]

As an aside, this must be MacRumors' largest & longest thread ever for a discussion - and it just has to win an award!

Behold, the golden apple:

Amiriiiiiight?

 

[Marche90]

Q (Software): Is it possible to create the OCLP USB installer with the (replacement) AMD GPU drivers already in place by preparing the USB on another machine ? When I look in Developer Settings on OCLP (GUI 0.4.10) - the option to select a specific MXM graphics card is not selectable.
Is there a workaround?

Q (Hardware): I (only) have Arctic MX-4 paste, and I bought some 0.5mm copper shims.
Is another kind of paste really needed for the VRAM?

Thank you in advance for any advice.

First question: Yes, it's possible to create it in another machine. Workaround for not being able to select the card is to use OCLP 0.4.6 TUI to select the type of MXM card.

Second: It's necessary, because the paste consistency is different. If you don't want to use paste, you can use thermal pads, though I remember reading it was less recommended.

 

[lsdc]

First question: Yes, it's possible to create it in another machine. Workaround for not being able to select the card is to use OCLP 0.4.6 TUI to select the type of MXM card.

Second: It's necessary, because the paste consistency is different. If you don't want to use paste, you can use thermal pads, though I remember reading it was less recommended.

Thank you. I suspected the TUI might be a route, but when they dropped it, I understood the narrative to be that the GUI made the TUI obsolete. I guess this is an edge case generally, but not around here...

Paste: Not what I wanted to hear, but thank you.

 

[Marche90]

Just bought a WX4150 (again... last time I did the seller was out of stock) and a Xeon E3 1270. Now the waiting game to supercharge my iMac begins.

 

[lsdc]

Thank you. I suspected the TUI might be a route, but when they dropped it, I understood the narrative to be that the GUI made the TUI obsolete. I guess this is an edge case generally, but not around here...

Paste: Not what I wanted to hear, but thank you.

Another Q: the large copper GPU board mounting plate has fixed screws on one side, and then larger spring-loaded screws on the other. Is it necessary to adjust these larger screws?

 

[curioussurfer]

Another Q: the large copper GPU board mounting plate has fixed screws on one side, and then larger spring-loaded screws on the other. Is it necessary to adjust these larger screws?

Just press the spring down with the thumb, when tightening the 4 small screws

 

[lsdc]

Just press the spring down with the thumb, when tightening the 4 small screws

Thank you.
I guess they are there as tensioners? I will not be tempted to overtighten.

I don't have the more viscous thermal compound, so will attempt to reuse/reposition the existing stuff onto the VRAM and the more prominent components on the replacement board.

(Just could not face the wait to get more compound; sometimes you have a window of opportunity and need to take it)

 

[lsdc]

Thank you.
I guess they are there as tensioners? I will not be tempted to overtighten.

I don't have the more viscous thermal compound, so will attempt to reuse/reposition the existing stuff onto the VRAM and the more prominent components on the replacement board.

(Just could not face the wait to get more compound; sometimes you have a window of opportunity and need to take it)

OK, I am reassembling now.

[ Minor setback (backtrack) in trapping AMB sensor cable behind the mainboard....]

Now, at the stage of reconnecting the airport card.

I cannot seem to reseat the connectors, and I am afraid of damaging them by pressing too hard.

Any advice?
Do they just need a bit of force?
Is there some trick?

(apologies for requesting this degree of hand-holding...)

 

[lsdc]

Now, at the stage of reconnecting the airport card.

I cannot seem to reseat the connectors, and I am afraid of damaging them by pressing too hard.

Is there some trick?

The trick is... to push them on.

Ugh. 😳

 

[lsdc]

The trick is... to push them on.

Ugh. 😳

Mainboard attached.
No RAM
No display

Power on:

LED 1 on
LED 2 flashing

My understanding is that this is a fault related to (main) power to the main board.

I removed main board completely and reassembled, with careful attention to reseating every cable....

Power on:

Same situation

Does this mean I have damaged the Power Supply (or cables/connectors)?

What are my options at this point?

(Feeling pretty deflated, as this is not even GPU related.... yet...)

 

[lsdc]

Mainboard attached.
No RAM
No display

Power on:

LED 1 on
LED 2 flashing

My understanding is that this is a fault related to (main) power to the main board.

Oh cr*p. Nothing like making a fool of yourself on a global platform.

So, you need some RAM to get to solid LED 2 (contrary to what Curtis Gross says here)

With one RAM module installed, I get solid LED 1 and 2.

But no LED 3.

However, according to the FAQ Hardware #22, that is to be expected with the AMD WX4130 GPU.

(I am beginning to learn...)

Onwards...

I am going to see if I can USB boot and flash bios via SSH without the LCD attached

(Apologies to all, for this stream of consciousness...)

 

[lsdc]

I am going to see if I can USB boot and flash bios via SSH without the LCD attached

TL;DR: iMac12,2 -> WX4130; OCLP/Monterey; black internal screen; minimal graphics on external screen

Update:

Was able to flash GPU via SSH. Saved old ROM to disk. Flashed new ROM; saved (back) new ROM. zero diff shows flash was successful. Here is the output from the flash write.

1 root@grml /lib/live/mount/persistence/sdb2/flash # ./amdvbflash -f -p 0 WX4130_GOP.rom
AMDVBFLASH version 4.71, Copyright (c) 2020 Advanced Micro Devices, Inc.

Old SSID: 17B0
New SSID: 0B04
Old P/N: BR20625.001
New P/N: 113-L10991-101
Old DeviceID: 67E8
New DeviceID: 67E8
Old Product Name: Dell/Compal Crane 15 BaffinM GL LE A1 GDDR5 4GB 300e/300m
New Product Name: Pegatron BaffinM GL PRO A1 GDDR5 4GB 214e/300m
Old BIOS Version: 015.050.000.001.020625
New BIOS Version: 015.050.000.001.000000
Flash type: M25P40/c
Burst size is 256
80000/80000h bytes programmed
80000/80000h bytes verified

Comment: The device ID checks out for a WX4130. The original ROM reassuringly has Dell in the string. I have no experience of the new ROM parameters, however, this is the ROM I picked up from the first page link.

Added new (completely box fresh Crucial MX500 1Tb) SSD
Reattached display.
Attached (pre-prepared) Monterey/OCLP external disk via USB->SATA cable (as boot drive) [set this up as iMac 12,2 with AMD GCN Legacy MXM card via the OCLP 0.4.6 TUI]

Boot: Healthy Mac boot tone; but a completely black screen; after a while fans kick in at full speed.

Tried:
Removing display and reinstalling with reseating all cables.
multiple NVRAM resets (began to feel like a minimalist electronic musician...)
Full SMC reset
Holding down Option key on boot
Removed power from (new) internal SATA SSD (and it remains disconnected)

Boot: same (black screen)

Attach external Apple Cinema display

Boot:
Main display: black screen
External display: boot picker, boot screen, login...

I'm in!

STATUS:
Fans on the machine at full speed.
Very slow graphics
Graphics: About this Mac: reports Graphics Display 8 MB (1920x1200 24bit).
System Report shows the same device ID as reported in the ROM flash and vendor as AMD.
WiFi: Yes
Bluetooth: Yes
Speakers: Yes
Camera: No

I have a (mostly) functioning (albeit slow) machine, with graphics only on an external display.

OCLP build on the machine itself (previously I prepped boot disk on another Mac) does NOT autodetect a Metal GPU.
If I manually select AMD GCN, build and install on the boot drive, then when I boot,
the machine gets so far in the OS load, and then goes into a boot loop.

I am not sure why this happens, but it is repeatable and happens with OCLP 0.4.6 TUI and 0.4.10 GUI.

So, if I then rebuild and install OCLP on this external boot drive on another Mac, and then put it back on the target iMac, I get back to the original booted (albeit slow) machine (STATUS as described above)

UGH.

Summary
The GPU flashing reports a Dell WX4130 and I have verified that the new boot ROM (linked from page 1) gets written to the card.
Mac low-level boot is OK (happy chime)

With Monterey/OCLP boot disk (prepared on another mac)
The main display is just... black.
External display works and Monterey boots fully
GPU identified correctly but feels like some kind of unaccelerated graphics mode.
Rebuild/install of OCLP on the external boot disk on the machine itself results in boot loop.

DISCLAIMER:
It's a new card. The vendor was attentive and careful to stress it was an original Dell product. (flash seems to confirm this). But I have not seen this card working myself.

---

I know the ethos of the thread is that you cannot diagnose faults remotely, but I would appreciate any thoughts/suggestions.

Questions
Q1: Does the presence of graphics on the external display indicate that the GPU card (hardware) is OK? (there's not some hidden way of getting a minimal graphics state without the GPU?)

Q2: there is a mention of a J4700 connector mod here. Has anyone had to do this with an AMD WX41*0 GPU? Is the pulling of these wires readily reversible?

Q3: I would like to try a Linux boot to check that the GPU card is ok. As this is now a non-standard iMac GPU, do I need a special install, or will the hardware / drivers be auto-detected? If anyone can point at a convenient USB package, I would be grateful.

What else should I be considering?

Many thanks in advance for any suggestions

 

[Ausdauersportler]

TL;DR: iMac12,2 -> WX4130; OCLP/Monterey; black internal screen; minimal graphics on external screen

Update:

Was able to flash GPU via SSH. Saved old ROM to disk. Flashed new ROM; saved (back) new ROM. zero diff shows flash was successful. Here is the output from the flash write.

1 root@grml /lib/live/mount/persistence/sdb2/flash # ./amdvbflash -f -p 0 WX4130_GOP.rom
AMDVBFLASH version 4.71, Copyright (c) 2020 Advanced Micro Devices, Inc.

Old SSID: 17B0
New SSID: 0B04
Old P/N: BR20625.001
New P/N: 113-L10991-101
Old DeviceID: 67E8
New DeviceID: 67E8
Old Product Name: Dell/Compal Crane 15 BaffinM GL LE A1 GDDR5 4GB 300e/300m
New Product Name: Pegatron BaffinM GL PRO A1 GDDR5 4GB 214e/300m
Old BIOS Version: 015.050.000.001.020625
New BIOS Version: 015.050.000.001.000000
Flash type: M25P40/c
Burst size is 256
80000/80000h bytes programmed
80000/80000h bytes verified

Comment: The device ID checks out for a WX4130. The original ROM reassuringly has Dell in the string. I have no experience of the new ROM parameters, however, this is the ROM I picked up from the first page link.

Added new (completely box fresh Crucial MX500 1Tb) SSD
Reattached display.
Attached (pre-prepared) Monterey/OCLP external disk via USB->SATA cable (as boot drive) [set this up as iMac 12,2 with AMD GCN Legacy MXM card via the OCLP 0.4.6 TUI]

Boot: Healthy Mac boot tone; but a completely black screen; after a while fans kick in at full speed.

Tried:
Removing display and reinstalling with reseating all cables.
multiple NVRAM resets (began to feel like a minimalist electronic musician...)
Full SMC reset
Holding down Option key on boot
Removed power from (new) internal SATA SSD (and it remains disconnected)

Boot: same (black screen)

Attach external Apple Cinema display

Boot:
Main display: black screen
External display: boot picker, boot screen, login...

I'm in!

STATUS:
Fans on the machine at full speed.
Very slow graphics
Graphics: About this Mac: reports Graphics Display 8 MB (1920x1200 24bit).
System Report shows the same device ID as reported in the ROM flash and vendor as AMD.
WiFi: Yes
Bluetooth: Yes
Speakers: Yes
Camera: No

I have a (mostly) functioning (albeit slow) machine, with graphics only on an external display.

OCLP build on the machine itself (previously I prepped boot disk on another Mac) does NOT autodetect a Metal GPU.
If I manually select AMD GCN, build and install on the boot drive, then when I boot,
the machine gets so far in the OS load, and then goes into a boot loop.

I am not sure why this happens, but it is repeatable and happens with OCLP 0.4.6 TUI and 0.4.10 GUI.

So, if I then rebuild and install OCLP on this external boot drive on another Mac, and then put it back on the target iMac, I get back to the original booted (albeit slow) machine (STATUS as described above)

UGH.

Summary
The GPU flashing reports a Dell WX4130 and I have verified that the new boot ROM (linked from page 1) gets written to the card.
Mac low-level boot is OK (happy chime)

With Monterey/OCLP boot disk (prepared on another mac)
The main display is just... black.
External display works and Monterey boots fully
GPU identified correctly but feels like some kind of unaccelerated graphics mode.
Rebuild/install of OCLP on the external boot disk on the machine itself results in boot loop.

DISCLAIMER:
It's a new card. The vendor was attentive and careful to stress it was an original Dell product. (flash seems to confirm this). But I have not seen this card working myself.

---

I know the ethos of the thread is that you cannot diagnose faults remotely, but I would appreciate any thoughts/suggestions.

Questions
Q1: Does the presence of graphics on the external display indicate that the GPU card (hardware) is OK? (there's not some hidden way of getting a minimal graphics state without the GPU?)

Q2: there is a mention of a J4700 connector mod here. Has anyone had to do this with an AMD WX41*0 GPU? Is the pulling of these wires readily reversible?

Q3: I would like to try a Linux boot to check that the GPU card is ok. As this is now a non-standard iMac GPU, do I need a special install, or will the hardware / drivers be auto-detected? If anyone can point at a convenient USB package, I would be grateful.

What else should I be considering?

Many thanks in advance for any suggestions

The WX4130 is not a GCN1-3 card in the sense OCLP uses the GCN tag, so just run OCLP without messing with flags you do not understand entirely.

The GOP vBIOS from the first post should enable with OC the internal LCD.

There are at least two vBIOS versions posted for different memory configs, a picture of the card would be more interesting than five long posts in 24h. It would have shown the vram vendor.

Post your saved vBIOS.

IMHO the GPU is working, you messed up building a proper OC and most likely flashed the wrong vBIOS.

 

[dfranetic]

Attached (pre-prepared) Monterey/OCLP external disk via USB->SATA cable (as boot drive) [set this up as iMac 12,2 with AMD GCN Legacy MXM card via the OCLP 0.4.6 TUI]

Boot: Healthy Mac boot tone; but a completely black screen; after a while fans kick in at full speed.

Why not connecting that new SSD via USB->SATA cable and installing OCLP there (on a different machine, as you wrote), then mount that SSD back into the iMac? (That way you'll actually have OC on the internal SSD.) Also, you have a Polaris card, not GCN1-3...

 

[Jforte]

TL;DR: iMac12,2 -> WX4130; OCLP/Monterey; black internal screen; minimal graphics on external screen

Update:

Was able to flash GPU via SSH. Saved old ROM to disk. Flashed new ROM; saved (back) new ROM. zero diff shows flash was successful. Here is the output from the flash write.

1 root@grml /lib/live/mount/persistence/sdb2/flash # ./amdvbflash -f -p 0 WX4130_GOP.rom
AMDVBFLASH version 4.71, Copyright (c) 2020 Advanced Micro Devices, Inc.

Old SSID: 17B0
New SSID: 0B04
Old P/N: BR20625.001
New P/N: 113-L10991-101
Old DeviceID: 67E8
New DeviceID: 67E8
Old Product Name: Dell/Compal Crane 15 BaffinM GL LE A1 GDDR5 4GB 300e/300m
New Product Name: Pegatron BaffinM GL PRO A1 GDDR5 4GB 214e/300m
Old BIOS Version: 015.050.000.001.020625
New BIOS Version: 015.050.000.001.000000
Flash type: M25P40/c
Burst size is 256
80000/80000h bytes programmed
80000/80000h bytes verified

Comment: The device ID checks out for a WX4130. The original ROM reassuringly has Dell in the string. I have no experience of the new ROM parameters, however, this is the ROM I picked up from the first page link.

Added new (completely box fresh Crucial MX500 1Tb) SSD
Reattached display.
Attached (pre-prepared) Monterey/OCLP external disk via USB->SATA cable (as boot drive) [set this up as iMac 12,2 with AMD GCN Legacy MXM card via the OCLP 0.4.6 TUI]

Boot: Healthy Mac boot tone; but a completely black screen; after a while fans kick in at full speed.

Tried:
Removing display and reinstalling with reseating all cables.
multiple NVRAM resets (began to feel like a minimalist electronic musician...)
Full SMC reset
Holding down Option key on boot
Removed power from (new) internal SATA SSD (and it remains disconnected)

Boot: same (black screen)

Attach external Apple Cinema display

Boot:
Main display: black screen
External display: boot picker, boot screen, login...

I'm in!

STATUS:
Fans on the machine at full speed.
Very slow graphics
Graphics: About this Mac: reports Graphics Display 8 MB (1920x1200 24bit).
System Report shows the same device ID as reported in the ROM flash and vendor as AMD.
WiFi: Yes
Bluetooth: Yes
Speakers: Yes
Camera: No

I have a (mostly) functioning (albeit slow) machine, with graphics only on an external display.

OCLP build on the machine itself (previously I prepped boot disk on another Mac) does NOT autodetect a Metal GPU.
If I manually select AMD GCN, build and install on the boot drive, then when I boot,
the machine gets so far in the OS load, and then goes into a boot loop.

I am not sure why this happens, but it is repeatable and happens with OCLP 0.4.6 TUI and 0.4.10 GUI.

So, if I then rebuild and install OCLP on this external boot drive on another Mac, and then put it back on the target iMac, I get back to the original booted (albeit slow) machine (STATUS as described above)

UGH.

Summary
The GPU flashing reports a Dell WX4130 and I have verified that the new boot ROM (linked from page 1) gets written to the card.
Mac low-level boot is OK (happy chime)

With Monterey/OCLP boot disk (prepared on another mac)
The main display is just... black.
External display works and Monterey boots fully
GPU identified correctly but feels like some kind of unaccelerated graphics mode.
Rebuild/install of OCLP on the external boot disk on the machine itself results in boot loop.

DISCLAIMER:
It's a new card. The vendor was attentive and careful to stress it was an original Dell product. (flash seems to confirm this). But I have not seen this card working myself.

---

I know the ethos of the thread is that you cannot diagnose faults remotely, but I would appreciate any thoughts/suggestions.

Questions
Q1: Does the presence of graphics on the external display indicate that the GPU card (hardware) is OK? (there's not some hidden way of getting a minimal graphics state without the GPU?)

Q2: there is a mention of a J4700 connector mod here. Has anyone had to do this with an AMD WX41*0 GPU? Is the pulling of these wires readily reversible?

Q3: I would like to try a Linux boot to check that the GPU card is ok. As this is now a non-standard iMac GPU, do I need a special install, or will the hardware / drivers be auto-detected? If anyone can point at a convenient USB package, I would be grateful.

What else should I be considering?

Many thanks in advance for any suggestions

Full fan speed is expected, because the ssd does not have a temperature sensor (the HDD has, you could buy a sata adaptor with a sensor to “glue” in the ssd, you could buy a second power and sata cable to attach a second disc from motherboard, the ssd can be putted behind the dvd drive and keep the 3.5 hdd or you can use Mac fan control app);
You can plug a external monitor and see image, that’a good…
Try to create a usb drive with “Windows to go” (with rufus, you can use a Windows 10 image) boot to Windows after (with the Windows to go usb drive), when the Windows is “on the normal run” use AMDVBFLASH (ATIFlash) to try to flash your gpu again with the custom bios (from this forum). Once is flashed, try again to boot MacOs…

 

[lsdc]

The WX4130 is not a GCN1-3 card in the sense OCLP uses the GCN tag, so just run OCLP without messing with flags you do not understand entirely.

The GOP vBIOS from the first post should enable with OC the internal LCD.

There are at least two vBIOS versions posted for different memory configs, a picture of the card would be more interesting than five long posts in 24h. It would have shown the vram vendor.

Post your saved vBIOS.

IMHO the GPU is working, you messed up building a proper OC and most likely flashed the wrong vBIOS.

My apologies for the verbosity

Thank you for the constructive suggestions

Attached are photos of GPU card and zip of the ROM extracted from the card.

The ROM I flashed onto card came from this post

 

[Ausdauersportler]

My apologies for the verbosity

Thank you for the constructive suggestions

Attached are photos of GPU card and zip of the ROM extracted from the card.

The ROM I flashed onto card came from this post

Somebody able to confirm my basic calculation:

According to the picture the memory type is Samsung K4G80325FB-HC28 which turns out to be a 8gbit chip (aka 1GB) - four of those are 4GB - the card is more likely a WX4150 4GB needing a different vBIOS?

Make a screen shot of the about this Mac window and post it...

Edit: It is a 4GB WX4150 - same performance, double memory.

 

[lsdc]

Somebody able to confirm my basic calculation:

According to the picture the memory type is Samsung K4G80325FB-HC28 which turns out to be a 8gbit chip (aka 1GB) - four of those are 4GB - the card is more likely a WX4150 4GB needing a different vBIOS?

Make a screen shot of the about this Mac window and post it...

Edit: It is a 4GB WX4150 - same performance, double memory.

I forgot to take a photo of my card before installation.
I wanted to respond quickly and could not face pulling the whole machine apart (again).
The photo I attached was from the vendor ad, but I notice that the ad has both 4130 and 4150 cards for sale (I ordered and paid for WX4130 and this was what was written (in pen) on the box on deliver)
So, I am sorry for this ambiguity.

The ROM I posted is that extracted from my card.
When I flashed, this was reported:

Old SSID: 17B0
New SSID: 0B04
Old P/N: BR20625.001
New P/N: 113-L10991-101
Old DeviceID: 67E8
New DeviceID: 67E8
Old Product Name: Dell/Compal Crane 15 BaffinM GL LE A1 GDDR5 4GB 300e/300m
New Product Name: Pegatron BaffinM GL PRO A1 GDDR5 4GB 214e/300m
Old BIOS Version: 015.050.000.001.020625
New BIOS Version: 015.050.000.001.000000
Flash type: M25P40/c
Burst size is 256
80000/80000h bytes programmed
80000/80000h bytes verified

The device ID seems to apply to both WX4130 and WX4150 cards.
This Product name suggests 4Gb - though I realise this is likely just a string field in the ROM file, not necessarily derived from the hardware itself?

 

[curioussurfer]

Here you will find Internetzel's 2 GOP wx4150 roms for alternative memory.

https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/page-635?post=30188251#post-30188251

 

[Ausdauersportler]

I forgot to take a photo of my card before installation.
I wanted to respond quickly and could not face pulling the whole machine apart (again).
The photo I attached was from the vendor ad, but I notice that the ad has both 4130 and 4150 cards for sale (I ordered and paid for WX4130 and this was what was written (in pen) on the box on deliver)
So, I am sorry for this ambiguity.

The ROM I posted is that extracted from my card.
When I flashed, this was reported:

Old SSID: 17B0
New SSID: 0B04
Old P/N: BR20625.001
New P/N: 113-L10991-101
Old DeviceID: 67E8
New DeviceID: 67E8
Old Product Name: Dell/Compal Crane 15 BaffinM GL LE A1 GDDR5 4GB 300e/300m
New Product Name: Pegatron BaffinM GL PRO A1 GDDR5 4GB 214e/300m
Old BIOS Version: 015.050.000.001.020625
New BIOS Version: 015.050.000.001.000000
Flash type: M25P40/c
Burst size is 256
80000/80000h bytes programmed
80000/80000h bytes verified

The device ID seems to apply to both WX4130 and WX4150 cards.
This Product name suggests 4Gb - though I realise this is likely just a string field in the ROM file, not necessarily derived from the hardware itself?

You are quite an expert! Read the docs, make a plan and stick to it. It is like playing Lego, in case you know Lego.
This cannot be replaced by mass postings here.

Your own screen shot claims your card has only 8MB of video memory.

Obviously you picked the wrong WX4130 vBIOS, try the one labeled with ALT. This can happen and for this reason @internetzel even quoted the existence of different version in his post. I should not mention that even the first post has an in depth discussion of this particular problem.

Flash the other vBIOS and you will be fine (hopefully)!

EDIT: The photo idea was mentioned on the plan on the first ....why do I write this?

 

[internetzel]

My apologies for the verbosity

Thank you for the constructive suggestions

Attached are photos of GPU card and zip of the ROM extracted from the card.

The ROM I flashed onto card came from this post

That VBIOS contains memory configurations a for 2 GB card (WX4130).

 

[thainglo]

@Ausdauersportler - I feel your pain. After kidding a couple iMacs over the month and reading a TON from this thread, you see repeat issues pop up over and over again.

Anyone lau ching this shoukd start by taking a picture of the new GPU - front and back, plus close up of RAM chips. Easy to do BEFORE it goes in the machine. Saved my bacon on my first mod when I flashed the wrong ROM as I had different RAM chips.

Take the pictures!