12-28-2010, 11:43 AM

Hey All,

I have a mac pro 3,1 I use for design. I have dual 27' apple monitors plugged in via dvi but i have been having some issues. For some reason recently the second monitor stopped displaying and shows only a black screen. If I switch the DVI plugs around the other one starts working and the one that was previously working fine displays a blank screen. This leads me to believe it has something to do with the power supply or more likely the graphics card. I'm using an ATI Radeon HD2600 with 256 MB of VRAM.

I have scoured the interwebs for a solution to this problem but have not been able to find a solution. Does anyone have any ideas on this?

Should I try buying a new graphics card? Is the power supply insufficient? Any help is GREATLY appreciated.

Thanks!

12-28-2010, 01:15 PM

Originally Posted by pickel182

I have dual 27' apple monitors plugged in via dvi but i have been having some issues. For some reason recently the second monitor stopped displaying and shows only a black screen. If I switch the DVI plugs around the other one starts working and the one that was previously working fine displays a blank screen.

The fact that when you switched the "plugs" the monitor that wasn't working worked...and the opposite for the other monitor..99% means that the video card is at least partially not working. The good thing is one of the ports works...rather than the whole video card not working.

If you need two monitors...then you have to get another video card. The positive is...if the new card has two ports on it...you will be able to run three monitors!

- Nick

p.s. A second thing to try is...open up your Mac Pro...remove the video card...and then reinstall it. Maybe it just needs to be reseated to get it to work properly again. It's a long shot...but worth a try.

12-28-2010, 01:37 PM

I am having similar issues with a Mac Pro. Different video card but the symptoms are the same. The card works fine as long as I don't have two monitors attached.

I doubt it is a power supply issue but just out of curiosity what else is installed that might be drawing power from the power supply (internal hard drives, dvd, other peripheral cards, etc.)?

12-28-2010, 03:18 PM

Originally Posted by Slydude

I am having similar issues with a Mac Pro. Different video card but the symptoms are the same. The card works fine as long as I don't have two monitors attached.

Are your symptoms the same as the OP? The OP's issue sounds like only one of the two DVI ports works (one is "dead" and the other one works).

Your situation sounds like if you have two monitors attached...neither port works.

Just curious,

- Nick

12-28-2010, 06:43 PM

I've got my 32" TV connected via a DVI-HDMI cable so I know one port works. If I switch the cable to the second port that port also works. If both ports are in use only one works.

I really need to move some gear around and test that again. I also need to once and for all rule out the cable run as an issue. I called Apple about this a while ago but at the time did not realize the pattern of there only being a problem when both ports are in use. Probably should test it before AppleCare expires.

12-28-2010, 10:29 PM

Originally Posted by Slydude

I've got my 32" TV connected via a DVI-HDMI cable so I know one port works. If I switch the cable to the second port that port also works. If both ports are in use only one works.

Thanks for the info. Yeah...that does seem sort of strange that each port works individually...but if both ports are occupied...only one works. Any chance the "reseating" the video card idea I mentioned to the OP might work for you?

If this were the "old days"...I might suggest that if two big monitors were plugged in, that you were running out of video ram. But most video cards these days (certainly a Mac Pro) would have more than enough vram to drive two monitors simultaneously.

Is this an older Mac Pro?...if so would you happen to have an X1900 video card. I remember there being a special replacement program involving the X1900 card. Here's an article on it:

Apple Admits to Problems with Mac Pro ATI X1900 XT Video Cards - Softpedia

HTH,

- Nick

12-28-2010, 11:33 PM

I think this model dates to early-mid 2007 if I remember correctly when I was searching a few months ago. It has an NVIDIA 7300 GT w 256 MB not the ATI. As I recall we avoided the ATI because iit conflicted with some games my wife was thinking about playing at the time.

Gotta look up my AppleCare info. It has either just expired recently or will very soon.

BTW Last time I worked on this reseating the card did not improve things a bit.