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Need some macintosh Sherlock Holmes genius help.

Y

YANewbie

macrumors newbie
Original poster
Aug 26, 2011
10
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Recently my quad core 3.1 MacPro running SL stopped displaying anything on my 24" Samsung monitor. It would start up to a black screen, and just stay that way.
I figured the Radeon X1900 video card inside had gone bad, so I put in an extra GTX285 I had laying around.
No change.
So, I pulled the drive and hooked it up to another MP and modified the system files so that it would allow screen sharing, and then restarted the troubling MacPro.
Through screen sharing I could see that the computer could ID that the graphics card was an nvidia card - but that was it. No details on the monitor it was hooked up to, or what model card I was running.
I shut it down, reinstalled the Radeon X1900, and started it up. Through screen sharing, I could see that the Radeon was completely recognized, and that the Samsung Syncmaster was also recognized - even though it wasn't showing anything. In the system profiler it just said "No Display Connected." (Remember this part :) )

So I grabbed an older Dell LCD, hooked it up to the MacPro, and the display came to life! I then unplugged from the Dell, and plugged back into the Samsung, and now it worked! But when I check the system profiler, it STILL says ""No Display Connected."
So now I'm thinking the Samsung needs a kickstart? Pretty weird so far, huh?
On reboots, however, the startup screen worked fine with the Radeon. From a cold start, it would stay black and then come to life after the computer had completed its startup routine.

So next I tested the GTX. I put it into another 2008 MacPro, and it worked perfectly. So the GTX is fine. I take a chance and put it back into the troublesome MacPro, and I'm back to square 1. No display response - from either the Samsung or the Dell, and the System Profile just shows an nvidia card with little detail. And, yes, I'm hooking up both power wires to the GTX as well - though I haven't run a voltage meter on them to see if their both working.
So, because the GTX still won't work, I put the Radeon back in, and nothing.
I have to go through the same process of hooking it up to the little Dell 14" before I get a picture, and then "hot swap" it to the Samsung 24" before I can get a picture on the Samsung.

Does this sound like a slowly frying MB? I hate to loose a MacPro like this - and granted, I should be happy the Radeon's working on it again. But I am completely baffled.

Thanks in advance for any comments or hints to try.
 
Have you installed OSX/firmware updates etc...?
Reset PRAM.
reset SMC?:

Resetting the SMC for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve

Shut down the computer.
Unplug the computer's power cord.
Wait fifteen seconds.
Attach the computer's power cord.
Wait five seconds, then press the power button to turn on the computer.
 
GTX is mac-compatible and works fine with my other 2008 Mac Pro.
I have p-Rammed and SMCed it to death, but the GTX won't turn anything on. Beginning to wonder if one of the power cords going to the card isn't functioning? Doesn't really explain the weird behavior with the Radeon needing a Dell monitor to help it "connect" though. Can we do firmware updates on the mac pros, or are those days gone?
Thanks again for trying. Anyone else?
 
Yes, I've switched cables and alternated the dual ports on the card as well. Thanks for the suggestion.

Does anyone think it could be something as simple as corrupted display drivers?
 
Do you see the gray screen and black apple at startup and the screen just goes black when the OS starts? Or is it always dark?

You said you had another MP - did you try the Radeon and monitor(s) in that machine?

If the card works in another machine and you at least get the gray screen at startup, try booting from the SL DVD and see if that works. That should isolate whether you have a SW or HW problem.

Have you tried both monitors on the other MP?

If you don't even get the initial gray screen at the chime, you have a HW problem, since OS X hasn't loaded yet. You need to do a controlled substitution of one part from the "bad" MP to the "good" MP at a time to isolate what is wrong.
 
The screen does nothing at all during boot up. On either monitor - when using the GTX 285.
The GTX 285 works fine on the other MP.
Both monitors work fine with the X1900 on the "bad" MP - didn't see a need to try them on the good one, but I suppose I could.
I have no other items on the "bad" MP to remove - other than swapping out motherboards, I suppose. Unless I'm missing something.
It's very strange, if I do say so myself. :(
Thanks for your suggestions.
 
YANewbie said:
The screen does nothing at all during boot up. On either monitor - when using the GTX 285.
The GTX 285 works fine on the other MP.
Both monitors work fine with the X1900 on the "bad" MP - didn't see a need to try them on the good one, but I suppose I could.
I have no other items on the "bad" MP to remove - other than swapping out motherboards, I suppose. Unless I'm missing something.
It's very strange, if I do say so myself. :(
Thanks for your suggestions.
Click to expand...

Huh? Not sure what you mean by "both monitors work fine with the X1900 on the bad MP" - isn't that what started this?
 
I suppose it is confusing unless you read through the entire thread.

Yes, the "bad" MP stopped displaying video using the X1900.
Put in the GTX285 and it didn't work either.
Put in the X1900 again, but to a different monitor, and it suddenly worked.
Swapped the 2nd monitor for the 1st monitor, and the 1st monitor works too.
Put the GTX285 in again, and no display works.
Put X1900 in again, hooked to 1st monitor - doesn't work.
Hook to 2nd monitor, it works.
Swap to 1st monitor, it works.

Computer recently crashed. On reboot, with X1900, display didn't work with either monitor.
Started up in single-user mode (blind, of course, with no display) and typed the fsck command to check disk. Waited five minutes, typed "reboot", and computer could then work with the 2nd display. Swapped out 2nd display for 1st display (larger one) and it works.

Very strange this. I think motherboard is damaged somehow and cannot handle large video display without first engaging a smaller display.

I have swapped out power cables to the video card, but I haven't tried hooking up an external power source to the card. Maybe the power supply is failing.

Thanks for all the input.
 
OP, try GTX 285 in other slot. Did you use the same power cables set in this other MP (where 285 worked)?
 
Interesting you bring up the power supply - that kinda makes sense. I have an external that's driving a GTX480 in the other PM. I'll try that tomorrow and get back. I think it's this or the mobo, but really hoping it this!! Good suggestions - thanks.
 
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