imac boots with black squares on white screen

jimbob61

macrumors newbie
Original poster
Jul 18, 2010
5
0
Dear all
recently my intel iMac 8.1 has been having problems, here's a rundown

screen would freeze then reboot after cooling down.
machine would freeze often
sometime machine would boot up again normally
machine would always boot up in safe mode.
sometimes machine would not boot up further than white apple logo.
top lefthand corner of machine becoming increasingly hot.
machine will not boot at all in safe mode.
machine now has a white screen with small black squares on boot up and will go no further.

Have tried the following remedies
set up new user account
repaired permissions on several occasions
run hardware test from disc showed up error Error on iMac 4mot/1/40000003: HDD - 1340 this suggests a hdd prob.
reinstalled OS X leopard from original disc then upgraded to snow leopard and then installed lion.
tried new hard drive

I have looked at various threads and they suggest hard drive problem to graphics card. I am trying to establish as close as possible what might be the problem. Any help appreciated.

Many thanks
jimbob61
 

pintsizemacman

macrumors regular
Sep 26, 2010
100
0
ohio
Your Graphics is failing... I recommend a low to medium end ATI replacement card (depending on what you are planning to do on the iMac).
 

jimbob61

macrumors newbie
Original poster
Jul 18, 2010
5
0
many thanks pintsizedmacman for the prompt reply. can you recommend a card and how easy or difficult is it to replace.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.