In desperate need of help! My 27" 09 iMac has artifacts all over the screen?

i having strange artifact issues on screen of 27" late 09 imac

specs....
i7 2.8hgz
8gb ram
ati radeon hd 4850 512 mb
osx mavericks os x 10.9.4


have never once had issue imac in years of owning until today.

running newest osx mavericks updated week released ( did few clean installs )

artifacts appearing on screen, anywhere colored lines, black boxes, mouse pointer disappearing ( though can still use it, can't see )

when go open program mail, safari, finer, etc. window appears black box, cannot see black box can still click on stuff , imac works fine, selected app using, visually cannot see or make out because either artifacts or black box.

parts of screen fine while others messed up. not entire screen,

tried fresh install of mavericks ( have on thumb drive ) , did thing , when finished , came time me input country, wireless password, etc. boxes displayed info crazy looking or totally missing not see continue button finish.

has been happening day, way can use imac without visual issues if working in safe mode ( in )

out of warranty , have no clue problem is? never once had issue imac, don't game, don't abuse it, don't install crazy programs.. of sudden started doing , way use imac in safe mode. don't clean install, reset pram, unplugged imac wall 15 mins, disconnected every single piece of hardware connected usb ports , still.

have clue issue may be? thinking video/graphics card going or dead (my imac has ati radeon hd 4850 512 mb graphics ) don't game never had need high end cards.

guessing (though wrong) isn't software issue , more hardware issue.

advice anyone? imac out of warranty , don't have funds fork on have apple store @ it.

 

hi maf2k8,

have same issue.

advised hardware problem: our graphics card being toasted.

researching solutions , reply if find 1

 

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