iMac not booting up screen has lines

[Saj]

Hi my iMac is not booting up and giving login prompt. I can login in safe mode fine. This started after I power cycled iMac Yesterday when it got hung . Moreover the display shows horizontal lines while booting and then cHanges to vertical lines

Any suggestions , thanks

 

[Cory Cooper]

Hello and welcome.

-Which exact model iMac?
-Which version of OS X/macOS?
-Can you post a few photos of what you are seeing on the display?
-Do you have an external monitor you can connect by chance to see if the issue is replicated on it?

C

 

[Saj]

Hello and welcome.

-Which exact model iMac?
-Which version of OS X/macOS?
-Can you post a few photos of what you are seeing on the display?
-Do you have an external monitor you can connect by chance to see if the issue is replicated on it?

C

Hi it’s 2008 iMac running El Capitan
See pic attached
I will try an external monitor now

 

[Saj]

I can’t attach screenshots it says file too large

 

[Cory Cooper]

OK, thanks.

A screenshot won't capture the lines probably...did you mean a photo? You can use Preview to open the photo and reduce the size, then upload.

C

 

[Saj]

I just uploaded two pictures, first during initial boot, next one further down in boot process

 

[Cory Cooper]

Hello,

I don't see them in your post...where did you upload them to?

C

 

[Saj]

I think upload failed again. Apple had me erase the hard drive and do a fresh install , but it failed. I just found the original cd that came back with iMac and made it startup disk. I see a blue screen now and it’s sitting there. How can I boot through cd and install the OS

 

[Saj]

Do you have an ideas