Checker board Screen

[Punkyclown]

Started up my Mac SE today and loaded the system (through an external drive).
Ran okay until I swapped out the disks, then the screen deteriorated with 
a butch of line that broke up the screen.  Shut it down and on subsequent restarts
all I get now is a checker board pattern on my screen.  Any ideas?
Thank you,
Brad Hansen

 

[bibilit]

Ram ?

 

[K55]

Might be ram isnt seated correctly or the ROM's are shot.