MP 1,1-5,1 DVI and VGA cables confusion/signal loss

[macstatic]

I've been having some trouble (black screen, won't boot properly -or so it seems, hard to tell when the screen is black!) with my cMP 5,1 lately. The BootROM has been confirmed corrupt (but has now been reconstructed reflashed back into my BootROM -thanks to tsialex!) but it also looks like my monitor cable was part of the problem (and confusion).
I'm now trying to narrow down the display issues, so here's my info and findings:

(image source: the-home-cinema-guide.com)

• My original Apple GPU (ATI Radeon HD-5870) has a single DVI connector (DVI-I dual linkaccording to the diagram above)
  • It's attached to my main monitor (1920 x 1200) with a DVI-D to DVI-D (single link) cable
  • I suspect the above cable to be faulty as the computer often boots/reboots without the screen displaying anything. At other times it's fine. I suspected a contact problem, but wiggling/moving it or its connectors around doesn't make the signal go away when I have a signal. I've had 2 or 3 exceptions where the screen has gone black after it's booted with the screen OK, but I don't know exactly how because I've been away from the computer for a while -so I've suspected the screen sleeping, but pressing keys/moving the mouse hasn't helped. Neither has wiggling the cable.
    
    One interesting finding is that when there's no signal (I have a black screen) I then disconnect/reconnect the cable at one particular end and the signal comes back! I've flipped the cable around (i.e. the monitor-end connector goes to the GPU-end if I had it the other way to begin with) but in that case the signal stays away, so my conclusion is there's something (but what?) problematic with one end of the cable (I've now marked it with a piece of tape.
    It also seems that I have to plug it firmly and quickly straight into the GPU connector (or monitor) to get the signal back. I don't know how this works, but perhaps DVI needs to have several signal pins connected simultaneously in order to synchronize and then send out the signal or something...
• I have another, smaller monitor (1280 x 1024) which I've just discovered can be used with my Mac (I've been using it with a vintage 80s computer) as it has both DVI and VGA connectors
  • I found a previously unused DVI-A to VGA cable, and it works great with this monitor and my cMP! No black screen so far.
  • The same new cable works great with my main monitor (which also has a VGA connector)
• With the above in mind I decided to try it out with my newly purchased "metal compatible" GPU (Sapphire HD-7950 Vapor-X OC boost). It has two DVI connectors, which (looking at the diagrams above) is a black DVI-D (dual link) closest to the top of the computer and a lower placed white DVI-I (dual link)connector next to the HDMI and DisplayPort connectors.
  • The (suspected faulty) DVI-D to DVI-D (single link) cable physically fits both upper (DVI-D dual link) and lower (DVI-I dual link) GPU connectors. Either of these connections gives a signal on the monitor
  • The new/unused cable (DVI-A to VGA) only physically fits the lower (white) GPU connector (DVI-I dual link), but gives no signal which puzzled me because it worked with the same connectors on the HD-5870 GPU. I've heard that PC GPU cards sometimes lose a few output signals when placed in a Mac -maybe that's it?
  • I'm not able to physically insert the new/unused cable (DVI-A to VGA) into the the upper (black) GPU connector (DVI-D dual link)

Another thing: with my new GPU (HD-7950) and the old cable (suspected to be faulty) I've noticed failed repeated boots (powering up, but also rebooting as far as I remember) where the screen goes black and stays that way....

I tried something new: first disconnect the cable from the GPU, then boot and wait till around the time the login window or (with an automatic login) the Finder desktop appears, then finally plug the cable back into the GPU. I need to check this many times of course for consistency (and with the other monitor as well), but it might seem that the signal needs to be there already in order to sync with the monitor. Are there any active electronics (i.e. electronic components as opposed to just wires connected together at each end) inside a DVI-D to DVI-D (single link) cable which could go bad?
Another thought: even though there aren't any obvious broken connections (i.e. the screen doesn't go black when I wiggle or move the cable around if I have a signal to begin with), could there be a weak connection (i.e. a wire with partly cut off strands) meaning that the signal passing is weak and the monitor will only sync up now and then at random, or that the differing logic state when the signal has already been generated (i.e. the GPU actually outputs something) makes a difference compared to a connection with no signal at first, then changing to having a signal. I really have no idea how DVI video works -just a few thoughts.
Can anyone make sense of all this and understand why I'm so often getting a black screen and what is going on with the mentioned DVI-D cable?

 

[Borowski]

Hello,
a few hints/questions:

- MacOS 10.13.6 is your main operating system?
- did you flash the 7950 for bootscreen-support or w/ stock bios?
- analog VGA is abandoned and not supported anymore; anyway, it works in some cases.
- you should get a brand-new DVI-cable to suspend issues
- usual DVI-cables are simple connectors without active parts
- perhaps the connector or pcb of the videocard has defects as it is mechanically stressed by frequently plugging the cable.

 

[macstatic]

Hello,
a few hints/questions:

- MacOS 10.13.6 is your main operating system?

Yes.
But I plan to try out MacOS 14 once I get this black screen stuff sorted out and see how that goes with running older 32-bit apps in Virtual Machines etc. before comitting to using that instead of 10.13.6.
Or maybe set up multiple startup drives to choose from.

- did you flash the 7950 for bootscreen-support or w/ stock bios?

Yes, using the method described post#1 of the "Guide to flash HD 7950/7970/280/280X for Mac EFI" thread (which I've summarized step-by-step myself here), but it apparently something's gone wrong as there's still no Mac bootscreen when holding down ALT upon booting.
I'm prepared to give it another go, but for now it's probably a good idea to get the black screen issue out of the way first.

- analog VGA is abandoned and not supported anymore; anyway, it works in some cases.

So it doesn't necessarily mean there's something wrong with the GPU when I'm not getting anything on the screen with it and the HD-7950?
By the way, how do the two DVI connectors on the HD-7950 work in relation to each other or used on their own? I never did get any user manual/info with my card (bought second hand).

- you should get a brand-new DVI-cable to suspend issues
- usual DVI-cables are simple connectors without active parts

Yes, even though the cause of the problem isn't obvious and logical it does indeed seem "something" is wrong with it.
Should I just get another one of the same kind (DVI-D to DVI-D single link) or another variant?

- perhaps the connector or pcb of the videocard has defects as it is mechanically stressed by frequently plugging the cable.

Good point!
I think I'll use a good magnifier and check both the cable and the GPU connectors for any bent pins, dirt etc. Maybe try out some contact spray.

Good advice! Thanks 👍👍👍

 

[Borowski]

Can you check in systemprofiler, if the modded bios was flashed?
Should look like this and the name of active framebuffer (should also show "ATY,Hamachi"):

https://forums.macrumors.com/attachments/sysinfo-jpg.790076/

Some variants of the cards are known to use slightly different hardware and won't fully work after flashing. Normally HDMI-port will be dead, but i don't know if other functions also been affected.

You should downgrade your card to unmodded factory-bios and do the same testing again.
For later versions of OSX Lion and newer, a pc-card could be fully initialized (ports, hardware-acceleration) by os, so flashing is only needed for cosmetic and bootscreen.

 

[macstatic]

Can you check in systemprofiler, if the modded bios was flashed?
Should look like this and the name of active framebuffer (should also show "ATY,Hamachi"):

https://forums.macrumors.com/attachments/sysinfo-jpg.790076/

I'm not sure how to interpret this, but here's what it says with the HD-7950 Vapor-X:

Some variants of the cards are known to use slightly different hardware and won't fully work after flashing. Normally HDMI-port will be dead, but i don't know if other functions also been affected.

I should probably search around the forum for others with this exact card (Sapphire HD-7950 Vapor-X with OC boost 3GB) who have performed a successful reflash and hear from their experiences.

You should downgrade your card to unmodded factory-bios and do the same testing again.
For later versions of OSX Lion and newer, a pc-card could be fully initialized (ports, hardware-acceleration) by os, so flashing is only needed for cosmetic and bootscreen.

Yes, it's the bootscreen I need.
Since I bought the card second hand with 2 previous owners I have no idea if it's been reflashed previously so it would be nice to "reset" it to the factory defaults. TechPowerUp has a bunch of firmware downloads for this card to choose from, but I really don't want to risk bricking the card by picking the wrong one.

 

[Borowski]

Seems it is unflashed: RadeonFramebuffer is the generic one from osx, used for non-flashed cards. Name is also wrong, "HD 7xxx" is ususally shown for pc-card, but its only cosmetic, the card should work.

So you can forget my ideas from previous posting.

 

[macstatic]

Thanks for checking.
Strange that it hasn't been flashed since I followed the procedure. I wrote a step-by-step summary here. Does it look correct?
There's also something strange sometimes (not always) when I power down, reboot or log out from my user where this comes up on an otherwise black screen:

Does this indicate something wrong or is it a common occurance with some GPUs? It's never happened with my HD-5870 (the screen just goes black in those situations).


About the DVI cable/black screen problem -some good news: I used an electronics contact-cleaner spray to clean both the (suspected faulty) DVI cable connectors and the two DVI connectors on the HD-7950. It seems to work a lot better now, and this behaviour seems consistent with one or several dirty contact pins. I'll continue checking, but this is promising!

Regarding using the two HD-7950 DVI connectors: it appears that with one monitor you can use either the upper or lower connector -it makes no difference.
But if I attach one monitor to the upper, and another one to the lower things change a bit:
-the one attached to the upper connector changes resolution (1200x1024 which is the resolution of the other monitor, instead of 1920x1200) so something is affecting it.

But there's nothing displayed on the other monitor (attached to the lower connector).
However, if I go to the "displays" system preference I see that two different monitors are attached!! That monitor is attached via a DVI-A to VGA cable. And even though this monitor attached with the same cable works fine with the HD-5870, why doesn't it work with the HD-7950? The connections are the same!:

HD-5870: DVI-I dual link with DVI-A to VGA cable
HD-7950: DVI-I dual link with DVI-A to VGA cable

So it must be a software issue.
Here's a screenshot of the "Displays" system preference. The "LCD1990SXI" is the monitor with the DVI-A to VGA cable.

 

[Borowski]

My fault, i didn't see the ports of this card yet: i wouldn't recommend this card as the connectors are completely different from the reference-model (1x DVI, 1x HDMI, 2x mDP) used for the "Sapphire HD 7950 Mac Edition"; this is mandatory for using w/ correct framebuffer-personality.

Best choice: Get the right card or use it unflashed w/ OC for bootscreen.

 

[macstatic]

Best choice: Get the right card or use it unflashed w/ OC for bootscreen.

Oh
I don't now if I'm prepared to shell out even more money for something like this. Could it be that the previous owner(s) had already reflashed it so that it no longer contains the original firmware? I suspect this because only one of the fans is spinning (but the other fan spins up for around 1-2 seconds, then stops when my cMP is turned on). I think I've come across forum threads where PC users have hacked/modified GPU firmware to allow for overclocking and such.

So if I try to reflash the GPU with an already modified firmware which might have shortcomings/problems, then no wonder I'm getting problems further down the line.

 

[Borowski]

You should flash the factory-rom first if you have doubts, the pre-owner(s) could have flashed wrong/modified rom. Wrong ram-timings/initialisation could cause the weird artefacts.

Can you boot Windows and read out the used VRAM with GPU-Z? I found two possible roms for your card, differ in used VRAM:
Elpida EDW2032BBBG: https://www.techpowerup.com/vgabios/142146/sapphire-hd7950-3072-130524
Hynix H5GQ2H24AFR: https://www.techpowerup.com/vgabios/131104/sapphire-hd7950-3072-120926-3

Before flashing, dump both stored roms, if the switch is for dual-bios-function. GPU-Z has also a rom-dump function. Perhaps one of the roms is untouched.

 

[macstatic]

You should flash the factory-rom first if you have doubts, the pre-owner(s) could have flashed wrong/modified rom. Wrong ram-timings/initialisation could cause the weird artefacts.

Yes, I think I should do that. Unfortunately the screen seems completely dead now and despite repeated attempts of attaching/disconnecting the DVI-D cable I'm not getting any signal. I'll just have to wait until the new cable arrives before doing anything else.
Come to think of it.... even though the cable doesn't seem to have a bad connection I realized that this isn't what I'm used to from the past (analog video) with flicker and the signal coming and going depending on the connection. I assume it's more like an ethernet connection which is lost. What do you think? In any case I'll be getting a new cable soon.
Fortunately I also have another Mac connected to the same network, and I'm even able to remotely log into the cMP if needed.

Can you boot Windows and read out the used VRAM with GPU-Z? I found two possible roms for your card, differ in used VRAM:
Elpida EDW2032BBBG: https://www.techpowerup.com/vgabios/142146/sapphire-hd7950-3072-130524
Hynix H5GQ2H24AFR: https://www.techpowerup.com/vgabios/131104/sapphire-hd7950-3072-120926-3

GPU-Z seems like a very helpful app for all this! I'm guessing it can even check which type of VRAM has been used. Probably a good idea to spend some time researching before reflashing (possibly with the wrong firmware).
https://www.techpowerup.com/vgabios/131104/sapphire-hd7950-3072-120926-3

Before flashing, dump both stored roms, if the switch is for dual-bios-function. GPU-Z has also a rom-dump function. Perhaps one of the roms is untouched.

Yes, maybe.
I already dumped it with the switch in the outer position.
When dumping the other switch position (the switch lights up in blue) -would I need to reboot (or power down and power up again) with that other switch position, or can I just change the switch position while in ATIwinflash, effectively dumping both ROM banks after each other? There seems to be a lot fo disagreement around this in various forum threads I've found concerning this card.

There's also disagreement on what the switch is for -some people say that when it's pushed in (lights up in blue) it means the "turbo" function is on. But perhaps both are correct -there are two variations of the firmware in each bank, and one of them is created for "turbo" (overclocked) use from the factory, but both banks can be overwritten with any firmware if needed. Does that sound correct?
I look forward to finding out more with GPU-Z when I get the replacement DVI-D cable. I ordered a "dual link" DVI-D type this time as it's backwards compatible with "single link" DVI-D connectors. Either it makes no difference or it improves upon things from what I've read.

 

[Borowski]

You must restart before getting dumps in the other switch-position (if its for dual-bios).

Attach both dumped files (attention: GPU-Z won't give different names for dumped files), i will compare in hex-editor.

 

[macstatic]

Thanks. I'll get back to you once I can see something on the screen again.

 

[macstatic]

You must restart before getting dumps in the other switch-position (if its for dual-bios).

Attach both dumped files (attention: GPU-Z won't give different names for dumped files), i will compare in hex-editor.

OK, the new DVI-D cable arrived and I'm back in business

Since I wasn't sure about my Windows setup I did it all again, on a physically separate drive in one of the cMP drive bays by following h9826790's step-by-step guide. I can boot into Windows now but haven't yet done steps 9 and onwards.
But since Windows (7) was working I tried running GPU-z (2.52.0) on that setup, but for some reason it reports "Standard VGA graphic adapter". I also find it strange that the Windows desktop is only a small square in the middle of my screen. I haven't messed with any of Windows' settings, so this happened from the very start (the last time I installed Windows as well). Maybe installing the additional Bootcamp software (steps 9 etc. from the above guide) will solve this?

 

[startergo]

You need to update the graphics driver. When you see Standard VGA driver that means a failsafe driver with the lowest resolution is set.

 

[macstatic]

Ah -yes, that makes sense. So this is likely the cause for both the tiny Windows desktop in the middle of my screen and the "standard VGA graphics adapter" info in GPU-z?

I really don't know my way around Windows: where should I go to find a driver for this particular card?
At the Sapphire website I found HD 7950 drivers for Windows 7, but I'm not sure which model of the 7950. Is this what I should install, or something else?

UPDATE: I went ahead and gave it a go. Sure enough, after installing and rebooting the entire screen was filled with the Windows desktop, and GPU-z now gives a more appropriate report. I'll get back here once I figure out some more Windows related issues (it's with good reason I never got into PCs!).

PS: can someone please tell me how to make screenshots within Windows 7 (with a Mac extended wired keyboard, but without the Bootcamp drivers)? It sure would make life easier than having to take photos of the screen.

 

[macstatic]

You must restart before getting dumps in the other switch-position (if its for dual-bios).

Attach both dumped files (attention: GPU-Z won't give different names for dumped files), i will compare in hex-editor.

Thanks for wanting to help me out.
Attached are firmware dumps for both switch positions of the "Sapphire HD-7950 Vapor-X OC with boost" (taking care to reboot after having pressed the switch) done both with AMDflash and GPU-Z.
It would be nice to find out if this is the original firmware that the card came with or not, and if not -should I perhaps find and download the original firmware to reflash the card with first, then proceed with the Mac reflashing procedure based on that?

Along with the firmware dumps attached, here are screenshots as well (from AMDflash and GPU-z):

Firmware switch position 1 (OUT)

Firmware switch position 2 (IN -blue LED in switch lights up)

You should flash the factory-rom first if you have doubts, the pre-owner(s) could have flashed wrong/modified rom. Wrong ram-timings/initialisation could cause the weird artefacts.

Can you boot Windows and read out the used VRAM with GPU-Z? I found two possible roms for your card, differ in used VRAM:
Elpida EDW2032BBBG: https://www.techpowerup.com/vgabios/142146/sapphire-hd7950-3072-130524
Hynix H5GQ2H24AFR: https://www.techpowerup.com/vgabios/131104/sapphire-hd7950-3072-120926-3

Before flashing, dump both stored roms, if the switch is for dual-bios-function. GPU-Z has also a rom-dump function. Perhaps one of the roms is untouched.

According to the GPU-z screenshots it looks to be Hynix memory chips.
I've looked up all available firmware downloadsfor the Sapphire HD/7950 at TechPowerUp and comparing this with the version GPU-Z reports I have in my 9750 Vapor-X OC with boost:

015.025.000.001.000000 (Jan 31, 2012)

two results come up with the same firmware:
Sapphire HD 7950 3GB BIOS (Vapor X)
Sapphire HD 7950 3GB BIOS

Neither of the above refer specifically to the "Vapor-X OC with boost" model. For that specific description I've found the following firmware versions:

015.034.000.005.000000 (May 24, 2013)
015.025.000.099.000000 (September 26, 2012)
015.025.000.099.000000 (September 26, 2012) -different link

There may be others as well (described as "Vapor X with boost", "Vapor-X OC boost", "Vapor X boost", "OC edition", "HD 7950 OC", "Boost", "Vapor X" and so on, but I don't know if these refer to the same card).
So which one should I download and reflash my card with in order to get it back to factory defaults (preferrably the latest firmware for my card as well, in case there have been bug fixes/improvements etc)?

My card's label says it's SKU# 11196-09.

Maybe someone reading has the same model card, purchased new (so they know it hasn't possibly been reflashed/hacked by a previous owner) and can share the factory installed firmware version number?

UPDATE: "HD 7950 with boost" at TechPowerUp appears to be the same GPU card as mine (even though the picture is wrong), if I compare it with the following info from the GPU-Z screenshot:

Device ID: 1002 679A
Subsystem ID: 174B 3000
Date: Dec-13-2012 (mine is older: Jan-31-2012)

Is this the one I should use to "factory default" reflash my card?
Can I go with firmware that has the same Device ID and a different Subsystem ID, or do they have to be exactly the same as my card?

Oh, wait! "Dual X boost" has the exact same Device ID and Subsystem ID and is dated Jan-8-2014!
The picture and description is wrong though. What do you think?

UPDATE NEW: come to think of it, the Device ID/subsystem ID numbers -don't they refer to the firmware?
So if the previous owner(s) flashed the card with the wrong firmware I would just be reflashing it with a different wrong firmware once again!
I need to find out which firmware belongs to the actual card. Or is GPU-Z already referring to the GPU card itself (regardless of which firmware has been put into its memory chips) with those ID numbers?