How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Travis Your Own Question
Travis
Travis, Mac-Trained Product Designer
Category: Mac
Satisfied Customers: 759
Experience:  19+ Years of Mac Experience, BSA in Design and 6 Years of Mac Training from University of Cincinnati
22842276
Type Your Mac Question Here...
Travis is online now
A new question is answered every 9 seconds

Why does a monitor get dots and broken images on the picture

Resolved Question:

Why does a monitor get dots and broken images on the picture? System is Apple.
Submitted: 6 years ago.
Category: Mac
Expert:  Travis replied 6 years ago.

Travis :

What type of mac? How old is it? What type of monitor and how old is it? When are these broken images and dots appearing and are they covering the entire screen or just part? The more info you can provide, the easier troubleshooting will be.

Customer :

G5 tower. Twin 2ghrtz. 3.5 gb ram. -- 2 flat screen monitors, 23" cinema HD display & 20" display -- Whole rig is 5 or 6 years old -- problem exists on both monitors -- Tiger on one drive, Leopard on another problem occurs when booted on either system, or even when booted from optical install disk or disc warrior disc

Customer :

problem has been intermitant for several months - repeated shut downs and startups would clear it up and machine would run ok for several days then happen again -- as of today, doesn't seem as if it's going to go away -- I' ve been told that i may have a bad graphics card -- also that i may have a bad driver off some sort -- card has two connectors for monitors

Customer :

When problem is severe, i lose control of machine

Travis :

Ok, because it is two different monitors, I'd rule out bad monitors.

Because it occurs when running from all different sources (hard drives, optical drives, etc), then I'd rule out software or system. I'd even rule out it being a bad driver, because it would mean that all drivers are corrupt on all startup drives. Very unlikely.

What's left? Video Card, Logic Board and RAM. Most likely culprit would be the video card. There are a few things you can do to make sure that it isn't the Mac itself and in board cache causing the issues. I'd suggest a PRAM reset and then a Safeboot. If the problem returns, I'd point at the video card.

First let's reset the PRAM on the computer.
1) Shut down the computer.
2) While the computer is shut down, locate these keys: command (has an apple on it), option (sometimes called alt), P, and R.
3) Turn the computer on, then press and hold Command-Option-P-R before the gray screen appears.
4) Hold these keys down until you hear the startup sound a total of 3 times.
5) Release the keys.

Next, let's try a Safe Boot. This will perform several clean up procedures that may be affecting the machine's performance and startup as well as clear out any cache here as well.
1) Shut down your computer completely.
2) Start up the computer and immediately after the startup chime, press and hold the Shift key
3) Once the gray Apple and progress indicator appear, release the Shift key
4) Note: Startup will likely take substantially longer than normal (20 - 30 minutes is not unheard of)
5) You should have to login to your account, even if it normally does so automatically.
6) Shut down the computer.
7) Restart and see how the monitors are acting.

Customer :

I should have mentioned something earlier that may be significant here. Early on in this trouble, I ran the Apple hardware test that came with the machine. I ran the long test - about 2 hours. It told me that everything tested OK. With this in mind, do you still think I should perform the actions you reccommended?

Travis :

Yes. Do both the PRAM reset and the Safeboot.

Customer :

Thanx, Travis. Will do. -- Phredd

Travis :

Good luck and keep me posted.

Customer :

Will try this tomorrow. Thanks for the info and if I need add'l assistance, I'll be back for another question and try to get you.

Travis and 4 other Mac Specialists are ready to help you