Pink screen on start up and does not boot

My 27" iMac (2011) no longer boots.

When starting, the chime goes as usual. The screen is pink with a grey apple logo. After a few minutes the screen goes all grey. Then after 30-40 second more, the computer restarts and goes through this same process.

I have reset PRAM/NVRAM, SMC. I have also tried to boot in safe mode (which isn't successful). It also doesn't run disk utility or diagnostics. I have also ran through fsck which no luck.

Before I take it to the Apple Store (which is a 4 hour round trip) is there anything else I should be checking? I have an SSD hard drive I've been waiting to install which would be the solution if it were the hard drive. But I'm not sure what the issue is and don't want to start installing an SSD when the graphics card has gone kaput.

Any help is greatly appreciated.

Thanks