Mac pro video problems. Computer or monitor?


macrumors newbie
Original poster
Aug 11, 2012
Hi everyone,

I'm hoping someone could shed some light on some problems i'm having with my mac Pro.

3.33 GHz 6-Core Intel Xeon running Mac OS X 10.6.8
graphics card: ATI Radeon HD 5770
display i'm using is a "Dell 2407 WFP"

2 weeks ago after returning from holiday i turned on the computer, no problems at first but then after a while the screen became black and there where white flickering kind of stripes rolling over the screen.

exactly the same as can be seen in this video only in my case after a while the screen just goes completely black:

i contacted Apple and since i had Apple care they decided to ship me a new ATI Radeon HD 5770 video card since the old one probably had a defect.

I Installed the new card and it seemed to work ok, now today...exact same problem with the new card. I tried everything, the only thing that seems to makes the screen jump on again is pulling out the power cable of the monitor and plug it back in...for a small time i can see my desktop again but then its back to the white striped black screen.

Also very weird is that right now after restarting i'm just working on my computer and don't seem to have any issues...whilst a half hour ago i had no video, even after turning it off a few times.

Dos this look/sound like a video card problem (again) or other mac pro hardware problem or is it a monitor problem, cable....

Should i contact Apple again and ask for a new video card or what am i to do, i'd hate to have my computer shipped out for 2 weeks as this is my bread and butter and have no other computer.

All help is greatly appreciated.

thnx folks


macrumors 6502
Apr 22, 2012
Sydney, Australia
Do you have the monitor plugged directly into the machine?

Usually a DVI extension cable or really long DVI cable will degrade the signal.

If this is the case you will need a powered DVI booster.

Having the same problem myself setting up this KVM, I get small flickers similar to yours but mainly in the black areas.


macrumors 604
Aug 5, 2010
Artifacts typically indicate a hardware problem of some kind. I've seen vertical lines with dying displays. This happened with some of the 30" ACDs as they were dying. Artifacts are more commonly gpu problems though. The way to test this would be to stress test the graphics. If the problem worsens, it's likely a gpu issue. Personally I wouldn't ship such a machine out if you depend on it for work. I'd order a replacement gpu for a couple hundred. You could try something like cinebench and their openGL test to see if artifacts worsen, although there is probably a better way. A dying cable is less likely.


macrumors 68000
May 8, 2008
Hilo, Hawai'i
If possible, try the oldie-but-goodie of switching to a different cable, and then a different port -- both on monitor and 5770.

In other words, if you're using MDP-->Displayport, then try the other MDP port on the 5770. Then try the DVI cable that most likely came with the Dell.


macrumors 603
Oct 22, 2007
An Island in the Salish Sea
Go with simple first. As stated above, change the cable and the port. But... also... borrow a monitor. If the problem persists then you know it's not the monitor.

Just my gut feeling... it's the monitor.


macrumors newbie
Original poster
Aug 11, 2012
Thank you all for replying and trying to help, its much appreciated.

I already tried out the following:

-Changed cable
- tried it out on a new monitor
- installed the replacement graphics card i got from Apple
-did the Apple hardware test

All without difference, at first the Apple spokesperson i had on the phone suggested this was a graphics card problem witch sounded realistic to me...but even with the new card i have these problems.

On some forums people claim this is due to driver problems of the card...if this is the case they could send out 5 more new cards without changing anything...if this would be the case what would you guys suggest i tell the guy/lady next time i call Apple.

The annoying thing is that its not all the time, for example yesterday i had the problem on and off the entire day resulting in not being able to finish my on the other hand the computer is running smooth, no issues. I'm not able to reproduce the artifacts...they just seem to happen randomly, sometimes after 5min. sometimes after 4 hours...sometimes i just runs for a few days without problem.


macrumors 68040
Dec 7, 2009
If it's driver issue all you can do is:
- clean install of 10.6
- upgrade to 10.7 (or 10.8) (clean install)
- replace card with one of Nvidias.
- try to fiddle with kexts from earlier 10.6 versions starting from 10.6.4 but this could be endless...


macrumors 6502
Oct 28, 2007
Does the problem persist if you switch to a lower screen resolution?

Seems like Trav

macrumors newbie
Sep 21, 2009
I have a similar problem myself. Same thing, (but much less drastic) but only when switching to lower resolutions (if my display setting is on the highest (native) setting, it's perfect, but if I play an old game and it automatically switches to 600 x 800, or something lower than 1024 x 768 for example, i get the flicker effect in Mac OS and Windows/bootcamp. I have a mac Pro with 4870 and have been trying to figure it out forever. I feel like it;s not a software issue as it;s done it with at least 3 different OSes, and i think if it was an issue wit the card hardware or cable it would do it all the time?


macrumors newbie
Dec 3, 2008
Same kind of problem with my hexacore macpro and same dell as you in my case white snow noise appears randomly. Try this: when white snow appears, turn off an then turn on the monitor. In my experience the system works fine again. Also you can try to make a screen capture when the problem appears, checking if the system is working properly under de faulty image.
I have read in other forums that there's some kind of incompatibility or problem with content protection mode betewen graphic card an monitor.
Pd. Excuse me for my poor english, i hope you has understood me.


macrumors newbie
Original poster
Aug 11, 2012
Hi guys,

Tried turning off the monitor but that doesn't help neither, only time when i have some succes is when i pull the power cable from the monitor and plug it back in...for some reason the screen looks ok again but often only for a short time, then its back to the black screen with white lines.

i did the Apple hardware test 2 times again today (extended) but the results came back as no problems found...does this actually mean its safe to say there is no hardware problem what-so-ever?

Only thing that has me puzzled is that if it actually is a software or incompatibility problem how come that i have this problem only since recently...i have the computer over a year and only now i'm getting these troubles.

Contacted Apple again and they decided to ship me another graphics card again, to be honest i don't think this is going to make any difference since they already replaced the graphics card 2 weeks ago for a new one.

a bit disappointing how apple claims they never heard of this problem before and claim that i'm the first one to encounter this...obviously there's loads of people around with similar issues...when i told this all he had to say was that the internet is not a reliable source for these kind of things.

I'm absolutely out of ideas here...


macrumors newbie
Dec 3, 2008
maybe you should borrow another monitor and see if it works correctly.
by the other way, my graphics card started to fail and discovered that the fan did not rotate, causing overheating, although in this case the macpro turned off. check your graphic card fans with the Mac Pro open when the problem appears.