Urrgh it's always tricky with a kernel panic before booting into OS, as it could be graphics, RAM, or even the HDD ... Is there an Apple Store local to you, or an Apple Repair Centre? Honestly it may be best to take it to a specialist for assessment.
If not, there are a few things you can try:
- Boot into recovery mode (CMD+R on startup). Have an external HDD or pendrive attached, and format this through Disk Utility. Select 'reinstall OS X' and set that to the external drive. That at least will give you a diagnostics HDD.
Now, if it either:
a) Begins downloading/installing OS X to the external drive, but never seems to complete the installation, it's likely not the HDD, and I suspect the issue would be RAM
b) If it installs OS X to the external drive without an issue, but when trying to boot into that external OS (hold Alt on startup) and it kernel panics as it currently is, I'd suspect GPU
c) Downloads/installs OS X to external drive without an issue, and boots into external OS without issue, it may be HDD.
Regardless, if it installs/boots into an external OS, please quote this as there are some additional diagnostics we can run.
Overall though, I still would suggest taking to an Apple Store if it's not too inconvenient.