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The Mac Pro First Generation is an Intel Xeon-based workstation computer manufactured by Apple Inc. The first generation model includes the machines from 2006 through 2008.

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Why can my Mac Pro early 2009 not maintain video output?

Hi. I bought this 4,1 2.66Ghz quad-core machine earlier this year, and everything seemed fine for a while. It came with a non-Apple GeForce 8800GT installed, and so it always booted with a black screen until the login interface came up. It came with El Capitan installed. I partitioned the drive and installed this Jan version of El Capitan in one partition, and Mountain Lion in the other, as this is where I have best access to my software, and this is my main boot. It came with 8GB of ram, which I upgraded to 16GB.

In the last couple of weeks the machine has refused to send a signal to my monitors, an NEC Multisync lcd2090uxi and its rebranded kin, a LaCie 320. The Apple chime sounds, and the machine whirrs happily away, booting up nicely, but no signal to the displays.

I found that I could prompt life to the displays by swapping round the DVI connectors, but as soon as I had to start-up, reboot, or wake the machine up from sleep it would be back to no signal again, and repeating the swap technique would then not help.

I am then in effect locked out of use of the machine.

I blamed the issue on the card and the vendor kindly sent me a replacement card...of the same model. The same problems have occurred, so my original card is not "faulty" per se.

The next way-in, I've found, was to swap the card to a different PCIe slot. This brought a signal back, so I wondered if slot 1 was failing. However, the cycle I've described before would then begin again. I found I could even replace the card back into slot 1 and get the same cycle of success and failure I've had before.

I've tried swapping the power cable to pcie aux b for both slots just in case aux a might've been failing, but to no avail. I've even tried reseating the processor tray, wildly-supposing there might be an issue there. All that achieved was a better seated processor tray.

I'll add that when I first had the machine I ran it to a LaCie Electron22Blue CRT with the LaCie 320 and everything was fine. I bought the NEC to replace the CRT behemoth, and the problems have started since then. The NEC was a cheap eBay find which I discovered has a power management issue, in that I could sent the 'puter to sleep but the NEC would stay warm with the screen faintly glowing, even tho' it told me that it was receiving no signal.

There is a part of me that wondered if this monitor might be the problem, but I don't see how as when it receives no signal it's telling me that, so surely it's not interacting with the card? The power management issue is a self-contained one, which just meant that I had to manually turn the display off, rather than depending on it going to sleep. Further-more, the issues occur even if the NEC is switched off.

Admittedly, I have not tried re-attaching the CRT yet. I am loathed to.

Looking online I see that there are issues with this model of card, but I can't see anything specific to my machine. It's either that or my PCIe assembly is the problem...or something else I haven't thought of.

BTW, I've tried zapped the PRAM... One chime? Which if I remember correctly is different to the old days which required three for zapping.

Any thoughts would be appreciated.

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I have found the answer to my problem. nVidia's GeForce 8800 GT might be stated to be Mac compatible, and even was a build option in earlier Mac Pros but user-purchased models will suffer problems after a time, at least on the early 2009 4,1 model. I have come to this conclusion as I decided to try using a second-hand example of the GT120 originally specified for the 4,1. One, may it be noted, that was taken from another Mac Pro and was installed by Apple originally.

My machine is now purring like a kitten.

Another suggestion is that you might have to find your own answers... It seems that some people simply don't have the good grace to be bothered enough to read your description of your problem properly, or take your own knowledge seriously, and they can waste your time...

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Please tell us more about this card, Is it a flashed (for Mac) card? AGP or PCI? I have had cards that one DVI port went out on and the second port works.

I really do not like the idea of partitioned drives with two systems. I prefer having that second system on a second drive. If for nothing else using one drive to check the other. I have also had issues with monitor drivers on machines with newer clean installs of 10.8 +.

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Thank you for your comment.

In all honesty I don't know if it was flashed for Mac. I see online that they are available from Nvidia for Mac, but if that would mean that it should give me the grey whirling daisy start-up window I don't know, because it is still a user installed card (tho' not by me). That very fact, along with the fact that it requires being attached to a pcie aux port for its power (I believe that the Apple installed cards such as the GT 120 were PCIe bus powered, tho' I might be wrong here), means that at the very least it is not an Apple-build component. Certainly the black screen till login (when the machine is behaving) means precisely that.

As for using two systems on two drives I use an OS on an external drive to do my servicing with.

The machine *had* been behaving since late January. It is only these last couple of weeks that this issue has arisen. It worked fine whenever I installed afresh.


BTW, as I stated in my original question, it is a PCIe (Express) card...


Please give us the Data printed on the card as to what it is. This is what my GT 120 looks like:

Except mine has two DVI ports

Here's the AGP with the telltale rear tag:

Putting an AGP card in s straight PCI-E slot may not work.


Both the cards (the one which came with the machine, and the replacement) are Nvidia GeForce 8800GT models. I believe they were one of the standard install options in 2008 Mac Pros.


What do you mean by "the AGP with the telltale rear tag"? The strange shape at the back end of the contact strip is where the retaining bar fits to hold the card in place. Again, the original card used to work just fine. It has only now started to cause problems


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Andy Bilewycz will be eternally grateful.
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