Mosaic effects on iMac screen not sure if this is a SuperUser question or AskDifferent question

When I start up my iMac 21.5" (Mid 2011 model) this morning, my screen looks like this:



Then the computer is completely frozen. Is the display card going to die? 

using Mac OS X 10.10.3, Graphics: AMD Radeon HD 6770M 512 MB
If you were looking to test the video card status I believe you could restart your iMac, hold the Option key right before the chime, and choose the Recovery disk. From there you can run system diagnostics.