crwdns2936637:0crwdne2936637:0 crwdns2853008:0crwdne2853008:0 crwdns2918746:0crwdne2918746:0
crwdns2918538:0crwdne2918538:0

crwdns2934243:0crwdne2934243:0 mayer

crwdns2934249:0crwdne2934249:0:

I had the same problem a couple of years ago. I'd try replacing the video card on your model.
+Here's how: https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+EMC+2389+GPU+Card+Replacement/6272
https://www.ifixit.com/Answers/View/153060/Has+artifacts+attached+to+the+desktop+icons+and+mouse+pointer.

crwdns2915684:0crwdne2915684:0:

open

crwdns2934241:0crwdne2934241:0 mayer

crwdns2934249:0crwdne2934249:0:

I had the same problem a couple of years ago.  I'd try replacing the video card on your model.

https://www.ifixit.com/Answers/View/153060/Has+artifacts+attached+to+the+desktop+icons+and+mouse+pointer.

crwdns2915684:0crwdne2915684:0:

open