Why do I have a pin-stripe screen?

My iMac screen went black, then when I re-started it, the entire screen had a narrow pin-stripe appearance. What might the problem be?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 3

crwdns2944067:02crwdne2944067:0:

Have you been able to fix the problem?

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

Please confirm the exact model

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

crwdns2934285:0crwdne2934285:0